diff --git a/src/document.cpp b/src/document.cpp
index 1b8aed8..d31144f 100644
--- a/src/document.cpp
+++ b/src/document.cpp
@@ -1,5 +1,6 @@
 #include "document.hpp"
 
+#include <new>
 #include <utility>
 
 #include <format>
@@ -86,28 +87,8 @@ namespace anm2ed
   Document& Document::operator=(Document&& other) noexcept
   {
     if (this != &other)
-    {
-      path = std::move(other.path);
-      snapshots = std::move(other.snapshots);
-      previewZoom = other.previewZoom;
-      previewPan = other.previewPan;
-      editorPan = other.editorPan;
-      editorZoom = other.editorZoom;
-      overlayIndex = other.overlayIndex;
-      regionBySpritesheet = std::move(other.regionBySpritesheet);
-      changeAllFramePropertiesRegionId = other.changeAllFramePropertiesRegionId;
-      hash = other.hash;
-      saveHash = other.saveHash;
-      autosaveHash = other.autosaveHash;
-      lastAutosaveTime = other.lastAutosaveTime;
-      isValid = other.isValid;
-      isOpen = other.isOpen;
-      isForceDirty = other.isForceDirty;
-      spritesheetHashes = std::move(other.spritesheetHashes);
-      spritesheetSaveHashes = std::move(other.spritesheetSaveHashes);
-      isAnimationPreviewSet = other.isAnimationPreviewSet;
-      isSpritesheetEditorSet = other.isSpritesheetEditorSet;
-    }
+      this->~Document();
+    new (this) Document(std::move(other));
     return *this;
   }
 
diff --git a/src/imgui/window/frame_properties.cpp b/src/imgui/window/frame_properties.cpp
index c0e1798..0758251 100644
--- a/src/imgui/window/frame_properties.cpp
+++ b/src/imgui/window/frame_properties.cpp
@@ -39,13 +39,17 @@ namespace anm2ed::imgui
 
       if (type == anm2::LAYER && document.reference.itemID != -1)
       {
-        auto spritesheetID = document.anm2.content.layers.at(document.reference.itemID).spritesheetID;
-        auto regionIt = document.regionBySpritesheet.find(spritesheetID);
-        if (regionIt != document.regionBySpritesheet.end() && !regionIt->second.ids.empty() &&
-            !regionIt->second.labels.empty())
+        if (auto layerIt = document.anm2.content.layers.find(document.reference.itemID);
+            layerIt != document.anm2.content.layers.end())
         {
-          regionLabels = regionIt->second.labels;
-          regionIds = regionIt->second.ids;
+          auto spritesheetID = layerIt->second.spritesheetID;
+          auto regionIt = document.regionBySpritesheet.find(spritesheetID);
+          if (regionIt != document.regionBySpritesheet.end() && !regionIt->second.ids.empty() &&
+              !regionIt->second.labels.empty())
+          {
+            regionLabels = regionIt->second.labels;
+            regionIds = regionIt->second.ids;
+          }
         }
       }
 
diff --git a/src/imgui/window/regions.cpp b/src/imgui/window/regions.cpp
index e135684..e91b6d2 100644
--- a/src/imgui/window/regions.cpp
+++ b/src/imgui/window/regions.cpp
@@ -482,6 +482,13 @@ namespace anm2ed::imgui
 
     if (ImGui::BeginPopupModal(propertiesPopup.label(), &propertiesPopup.isOpen, ImGuiWindowFlags_NoResize))
     {
+      if (!spritesheet || (reference != -1 && !spritesheet->regions.contains(reference)))
+      {
+        propertiesPopup.close();
+        ImGui::EndPopup();
+        return;
+      }
+
       auto childSize = child_size_get(5);
       auto& region = reference == -1 ? editRegion : spritesheet->regions.at(reference);
 
diff --git a/src/imgui/window/spritesheet_editor.cpp b/src/imgui/window/spritesheet_editor.cpp
index 0801b25..0defad8 100644
--- a/src/imgui/window/spritesheet_editor.cpp
+++ b/src/imgui/window/spritesheet_editor.cpp
@@ -227,10 +227,13 @@ namespace anm2ed::imgui
           }
         }
 
+        auto layerIt = anm2.content.layers.find(reference.itemID);
+        bool isReferenceLayerOnSpritesheet =
+            frame && reference.itemID > -1 && layerIt != anm2.content.layers.end() &&
+            layerIt->second.spritesheetID == referenceSpritesheet;
+
         int highlightedRegionId = -1;
-        if (frame && reference.itemID > -1 &&
-            anm2.content.layers.at(reference.itemID).spritesheetID == referenceSpritesheet && frame->regionID != -1 &&
-            spritesheet->regions.contains(frame->regionID))
+        if (isReferenceLayerOnSpritesheet && frame->regionID != -1 && spritesheet->regions.contains(frame->regionID))
         {
           highlightedRegionId = frame->regionID;
         }
@@ -271,8 +274,7 @@ namespace anm2ed::imgui
           }
         }
 
-        bool isFrameOnSpritesheet =
-            frame && reference.itemID > -1 && anm2.content.layers.at(reference.itemID).spritesheetID == referenceSpritesheet;
+        bool isFrameOnSpritesheet = isReferenceLayerOnSpritesheet;
         if (isFrameOnSpritesheet && frame->regionID == -1)
         {
           auto frameModel = math::quad_model_get(frame->size, frame->crop);
@@ -338,6 +340,10 @@ namespace anm2ed::imgui
         auto isMod = ImGui::IsKeyDown(ImGuiMod_Shift);
 
         auto frame = document.frame_get();
+        auto layerIt = anm2.content.layers.find(reference.itemID);
+        bool isReferenceLayerOnSpritesheet =
+            frame && reference.itemID > -1 && layerIt != anm2.content.layers.end() &&
+            layerIt->second.spritesheetID == referenceSpritesheet;
         auto useTool = tool;
         auto step = isMod ? STEP_FAST : STEP;
         auto stepX = isGridSnap ? step * gridSize.x : step;
@@ -440,8 +446,7 @@ namespace anm2ed::imgui
             {
               regionReference = hoveredRegionId;
               regionSelection = {hoveredRegionId};
-              if (frame && reference.itemID > -1 &&
-                  anm2.content.layers.at(reference.itemID).spritesheetID == referenceSpritesheet)
+              if (isReferenceLayerOnSpritesheet)
               {
                 DOCUMENT_EDIT(document, localize.get(EDIT_FRAME_REGION), Document::FRAMES,
                               {
diff --git a/src/imgui/window/timeline.cpp b/src/imgui/window/timeline.cpp
index d6cc570..1b4502c 100644
--- a/src/imgui/window/timeline.cpp
+++ b/src/imgui/window/timeline.cpp
@@ -653,17 +653,33 @@ namespace anm2ed::imgui
       ImGui::PushID(index);
 
       auto item = animation ? animation->item_get(type, id) : nullptr;
+      if (type != anm2::NONE && !item)
+      {
+        ImGui::PopID();
+        return;
+      }
       auto isVisible = item ? item->isVisible : false;
       auto& isOnlyShowLayers = settings.timelineIsOnlyShowLayers;
       if (isOnlyShowLayers && type != anm2::LAYER) isVisible = false;
       auto isReferenced = reference.itemType == type && reference.itemID == id;
 
-      auto label = type == anm2::LAYER ? std::vformat(localize.get(FORMAT_LAYER),
-                                                      std::make_format_args(id, anm2.content.layers[id].name,
-                                                                            anm2.content.layers[id].spritesheetID))
-                   : type == anm2::NULL_
-                       ? std::vformat(localize.get(FORMAT_NULL), std::make_format_args(id, anm2.content.nulls[id].name))
-                       : localize.get(anm2::TYPE_STRINGS[type]);
+      auto label = [&]() -> std::string
+      {
+        if (type == anm2::LAYER)
+        {
+          auto it = anm2.content.layers.find(id);
+          if (it == anm2.content.layers.end()) return localize.get(anm2::TYPE_STRINGS[type]);
+          return std::vformat(localize.get(FORMAT_LAYER),
+                              std::make_format_args(id, it->second.name, it->second.spritesheetID));
+        }
+        if (type == anm2::NULL_)
+        {
+          auto it = anm2.content.nulls.find(id);
+          if (it == anm2.content.nulls.end()) return localize.get(anm2::TYPE_STRINGS[type]);
+          return std::vformat(localize.get(FORMAT_NULL), std::make_format_args(id, it->second.name));
+        }
+        return localize.get(anm2::TYPE_STRINGS[type]);
+      }();
       auto icon = anm2::TYPE_ICONS[type];
       auto iconTintCurrent = isLightTheme && type == anm2::NONE ? ImVec4(1.0f, 1.0f, 1.0f, 1.0f) : itemIconTint;
       auto baseColorVec = item_color_vec(type);
@@ -699,7 +715,9 @@ namespace anm2ed::imgui
           ImGui::SetNextItemStorageID(id);
           if (ImGui::Selectable("##Item Button", isReferenced, ImGuiSelectableFlags_SelectOnClick, itemSize))
           {
-            if (type == anm2::LAYER) document.spritesheet.reference = anm2.content.layers[id].spritesheetID;
+            if (type == anm2::LAYER)
+              if (auto it = anm2.content.layers.find(id); it != anm2.content.layers.end())
+                document.spritesheet.reference = it->second.spritesheetID;
             reference_set_item(type, id);
           }
           ImGui::PopStyleColor(3);
@@ -743,7 +761,9 @@ namespace anm2ed::imgui
                 }
                 case anm2::LAYER:
                 {
-                  auto& layer = anm2.content.layers[id];
+                  auto it = anm2.content.layers.find(id);
+                  if (it == anm2.content.layers.end()) break;
+                  auto& layer = it->second;
                   ImGui::PushFont(resources.fonts[font::BOLD].get(), font::SIZE);
                   ImGui::TextUnformatted(layer.name.c_str());
                   ImGui::PopFont();
@@ -760,7 +780,9 @@ namespace anm2ed::imgui
                 }
                 case anm2::NULL_:
                 {
-                  auto& nullInfo = anm2.content.nulls[id];
+                  auto it = anm2.content.nulls.find(id);
+                  if (it == anm2.content.nulls.end()) break;
+                  auto& nullInfo = it->second;
                   ImGui::PushFont(resources.fonts[font::BOLD].get(), font::SIZE);
                   ImGui::TextUnformatted(nullInfo.name.c_str());
                   ImGui::PopFont();
@@ -853,18 +875,21 @@ namespace anm2ed::imgui
 
           if (type == anm2::NULL_)
           {
-            auto& null = anm2.content.nulls.at(id);
-            auto& isShowRect = null.isShowRect;
-            auto rectIcon = isShowRect ? icon::SHOW_RECT : icon::HIDE_RECT;
-            ImGui::SetCursorPos(
-                ImVec2(itemSize.x - (ImGui::GetTextLineHeightWithSpacing() * 2) - ImGui::GetStyle().ItemSpacing.x,
-                       (itemSize.y - ImGui::GetTextLineHeightWithSpacing()) / 2));
-            if (ImGui::ImageButton("##Rect Toggle", resources.icons[rectIcon].id, icon_size_get()))
-              DOCUMENT_EDIT(document, localize.get(EDIT_TOGGLE_NULL_RECT), Document::FRAMES,
-                            null.isShowRect = !null.isShowRect);
-            overlay_icon(resources.icons[rectIcon].id, iconTintCurrent);
-            ImGui::SetItemTooltip("%s", isShowRect ? localize.get(TOOLTIP_NULL_RECT_SHOWN)
-                                                   : localize.get(TOOLTIP_NULL_RECT_HIDDEN));
+            if (auto it = anm2.content.nulls.find(id); it != anm2.content.nulls.end())
+            {
+              auto& null = it->second;
+              auto& isShowRect = null.isShowRect;
+              auto rectIcon = isShowRect ? icon::SHOW_RECT : icon::HIDE_RECT;
+              ImGui::SetCursorPos(
+                  ImVec2(itemSize.x - (ImGui::GetTextLineHeightWithSpacing() * 2) - ImGui::GetStyle().ItemSpacing.x,
+                         (itemSize.y - ImGui::GetTextLineHeightWithSpacing()) / 2));
+              if (ImGui::ImageButton("##Rect Toggle", resources.icons[rectIcon].id, icon_size_get()))
+                DOCUMENT_EDIT(document, localize.get(EDIT_TOGGLE_NULL_RECT), Document::FRAMES,
+                              null.isShowRect = !null.isShowRect);
+              overlay_icon(resources.icons[rectIcon].id, iconTintCurrent);
+              ImGui::SetItemTooltip("%s", isShowRect ? localize.get(TOOLTIP_NULL_RECT_SHOWN)
+                                                     : localize.get(TOOLTIP_NULL_RECT_HIDDEN));
+            }
           }
 
           ImGui::PopStyleVar(2);
@@ -1229,7 +1254,9 @@ namespace anm2ed::imgui
             bool isDifferentItem = reference.itemType != type || reference.itemID != id;
             if (ImGui::Selectable("##Frame Button", isSelected, ImGuiSelectableFlags_None, buttonSize))
             {
-              if (type == anm2::LAYER) document.spritesheet.reference = anm2.content.layers[id].spritesheetID;
+              if (type == anm2::LAYER)
+                if (auto it = anm2.content.layers.find(id); it != anm2.content.layers.end())
+                  document.spritesheet.reference = it->second.spritesheetID;
 
               if (type != anm2::TRIGGER)
               {
@@ -1275,11 +1302,12 @@ namespace anm2ed::imgui
                 frameDragDrop.type = type;
                 frameDragDrop.itemID = id;
                 frameDragDrop.animationIndex = reference.animationIndex;
+                frameSelectionLocked.clear();
 
                 auto append_valid_indices = [&](const auto& container)
                 {
                   for (auto idx : container)
-                    if (idx >= 0 && idx < (int)item->frames.size()) frameDragDrop.selection.push_back(idx);
+                    if (idx >= 0 && idx < (int)item->frames.size()) frameSelectionLocked.push_back(idx);
                 };
 
                 if (isReferenced) append_valid_indices(frames.selection);
@@ -1287,27 +1315,26 @@ namespace anm2ed::imgui
                 auto contains_index = [&](const std::vector<int>& container, int index)
                 { return std::find(container.begin(), container.end(), index) != container.end(); };
 
-                if ((!contains_index(frameDragDrop.selection, (int)i) || frameDragDrop.selection.size() <= 1) &&
+                if ((!contains_index(frameSelectionLocked, (int)i) || frameSelectionLocked.size() <= 1) &&
                     frameSelectionSnapshotReference.animationIndex == reference.animationIndex &&
                     frameSelectionSnapshotReference.itemType == type && frameSelectionSnapshotReference.itemID == id &&
                     contains_index(frameSelectionSnapshot, (int)i))
                 {
-                  frameDragDrop.selection = frameSelectionSnapshot;
+                  frameSelectionLocked = frameSelectionSnapshot;
                   frames.selection.clear();
                   for (int idx : frameSelectionSnapshot)
                     if (idx >= 0 && idx < (int)item->frames.size()) frames.selection.insert(idx);
-                  frameSelectionLocked = frameDragDrop.selection;
                   isFrameSelectionLocked = true;
                 }
 
-                if (frameDragDrop.selection.empty()) frameDragDrop.selection.push_back((int)i);
+                if (frameSelectionLocked.empty()) frameSelectionLocked.push_back((int)i);
 
-                std::sort(frameDragDrop.selection.begin(), frameDragDrop.selection.end());
-                frameDragDrop.selection.erase(
-                    std::unique(frameDragDrop.selection.begin(), frameDragDrop.selection.end()),
-                    frameDragDrop.selection.end());
+                std::sort(frameSelectionLocked.begin(), frameSelectionLocked.end());
+                frameSelectionLocked.erase(std::unique(frameSelectionLocked.begin(), frameSelectionLocked.end()),
+                                           frameSelectionLocked.end());
 
-                ImGui::SetDragDropPayload(FRAME_DRAG_PAYLOAD_ID, &frameDragDrop, sizeof(FrameDragDrop));
+                frameDragDropPayload = {type, id, reference.animationIndex};
+                ImGui::SetDragDropPayload(FRAME_DRAG_PAYLOAD_ID, &frameDragDropPayload, sizeof(frameDragDropPayload));
                 ImGui::EndDragDropSource();
               }
 
@@ -1315,7 +1342,7 @@ namespace anm2ed::imgui
               {
                 if (auto payload = ImGui::AcceptDragDropPayload(FRAME_DRAG_PAYLOAD_ID))
                 {
-                  auto source = static_cast<const FrameDragDrop*>(payload->Data);
+                  auto source = static_cast<const FrameDragDropPayload*>(payload->Data);
                   auto sameAnimation = source && source->animationIndex == reference.animationIndex;
                   auto sourceItem =
                       sameAnimation && animation ? animation->item_get(source->type, source->itemID) : nullptr;
@@ -1333,7 +1360,7 @@ namespace anm2ed::imgui
 
                   if (source && sourceItem && targetItem && source->type != anm2::TRIGGER && type != anm2::TRIGGER)
                   {
-                    std::vector<int> indices = source->selection;
+                    std::vector<int> indices = frameSelectionLocked;
                     if (indices.empty()) indices.push_back((int)i);
                     std::sort(indices.begin(), indices.end());
                     indices.erase(std::unique(indices.begin(), indices.end()), indices.end());
@@ -1387,7 +1414,8 @@ namespace anm2ed::imgui
                       document.frameTime = time_from_index(targetItem, reference.frameIndex);
                       if (type == anm2::LAYER)
                       {
-                        document.spritesheet.reference = anm2.content.layers[id].spritesheetID;
+                        if (auto it = anm2.content.layers.find(id); it != anm2.content.layers.end())
+                          document.spritesheet.reference = it->second.spritesheetID;
                       }
                     }
                   }
@@ -1496,6 +1524,7 @@ namespace anm2ed::imgui
           draggedFrameStart = -1;
           draggedFrameStartDuration = -1;
           isDraggedFrameSnapshot = false;
+          frameSelectionLocked.clear();
           if (type == anm2::TRIGGER) item->frames_sort_by_at_frame();
         }
       }
@@ -1858,23 +1887,29 @@ namespace anm2ed::imgui
 
             if (type == anm2::LAYER)
             {
-              auto& layer = anm2.content.layers[id];
-              auto label =
-                  std::vformat(localize.get(FORMAT_LAYER), std::make_format_args(id, layer.name, layer.spritesheetID));
-              if (ImGui::Selectable(label.c_str(), isSelected))
+              if (auto it = anm2.content.layers.find(id); it != anm2.content.layers.end())
               {
-                addItemID = id;
-                addItemSpritesheetID = layer.spritesheetID;
+                auto& layer = it->second;
+                auto label = std::vformat(localize.get(FORMAT_LAYER),
+                                          std::make_format_args(id, layer.name, layer.spritesheetID));
+                if (ImGui::Selectable(label.c_str(), isSelected))
+                {
+                  addItemID = id;
+                  addItemSpritesheetID = layer.spritesheetID;
+                }
               }
             }
             else if (type == anm2::NULL_)
             {
-              auto& null = anm2.content.nulls[id];
-              auto label = std::vformat(localize.get(FORMAT_NULL), std::make_format_args(id, null.name));
-              if (ImGui::Selectable(label.c_str(), isSelected))
+              if (auto it = anm2.content.nulls.find(id); it != anm2.content.nulls.end())
               {
-                addItemID = id;
-                addItemIsShowRect = null.isShowRect;
+                auto& null = it->second;
+                auto label = std::vformat(localize.get(FORMAT_NULL), std::make_format_args(id, null.name));
+                if (ImGui::Selectable(label.c_str(), isSelected))
+                {
+                  addItemID = id;
+                  addItemIsShowRect = null.isShowRect;
+                }
               }
             }
 
@@ -2009,16 +2044,16 @@ namespace anm2ed::imgui
       auto isNextFrame = shortcut(manager.chords[SHORTCUT_NEXT_FRAME], shortcut::GLOBAL);
 
       if (isPreviousFrame)
-        if (auto item = document.item_get(); !item->frames.empty())
+        if (auto item = document.item_get(); item && !item->frames.empty())
           reference.frameIndex = glm::clamp(--reference.frameIndex, 0, (int)item->frames.size() - 1);
 
       if (isNextFrame)
-        if (auto item = document.item_get(); !item->frames.empty())
+        if (auto item = document.item_get(); item && !item->frames.empty())
           reference.frameIndex = glm::clamp(++reference.frameIndex, 0, (int)item->frames.size() - 1);
 
       if (isPreviousFrame || isNextFrame)
       {
-        if (auto item = document.item_get(); !item->frames.empty())
+        if (auto item = document.item_get(); item && !item->frames.empty())
         {
           frames_selection_set_reference();
           document.frameTime = item->frame_time_from_index_get(reference.frameIndex);
diff --git a/src/imgui/window/timeline.hpp b/src/imgui/window/timeline.hpp
index d75910c..761f27c 100644
--- a/src/imgui/window/timeline.hpp
+++ b/src/imgui/window/timeline.hpp
@@ -15,7 +15,13 @@ namespace anm2ed::imgui
     anm2::Type type{anm2::NONE};
     int itemID{-1};
     int animationIndex{-1};
-    std::vector<int> selection{};
+  };
+
+  struct FrameDragDropPayload
+  {
+    anm2::Type type{anm2::NONE};
+    int itemID{-1};
+    int animationIndex{-1};
   };
 
   class Timeline
@@ -39,6 +45,7 @@ namespace anm2ed::imgui
     bool frameFocusRequested{};
     int frameFocusIndex{-1};
     FrameDragDrop frameDragDrop{};
+    FrameDragDropPayload frameDragDropPayload{};
     std::vector<int> frameSelectionSnapshot{};
     std::vector<int> frameSelectionLocked{};
     bool isFrameSelectionLocked{};
diff --git a/src/imgui/wizard/change_all_frame_properties.cpp b/src/imgui/wizard/change_all_frame_properties.cpp
index e1af3d7..d861db6 100644
--- a/src/imgui/wizard/change_all_frame_properties.cpp
+++ b/src/imgui/wizard/change_all_frame_properties.cpp
@@ -234,9 +234,13 @@ namespace anm2ed::imgui::wizard
     const Storage* regionStorage = nullptr;
     if (itemType == anm2::LAYER && document.reference.itemID != -1)
     {
-      auto spritesheetID = document.anm2.content.layers.at(document.reference.itemID).spritesheetID;
-      auto regionIt = document.regionBySpritesheet.find(spritesheetID);
-      if (regionIt != document.regionBySpritesheet.end()) regionStorage = &regionIt->second;
+      if (auto layerIt = document.anm2.content.layers.find(document.reference.itemID);
+          layerIt != document.anm2.content.layers.end())
+      {
+        auto spritesheetID = layerIt->second.spritesheetID;
+        auto regionIt = document.regionBySpritesheet.find(spritesheetID);
+        if (regionIt != document.regionBySpritesheet.end()) regionStorage = &regionIt->second;
+      }
     }
     auto regionIds = regionStorage && !regionStorage->ids.empty() ? regionStorage->ids : fallbackIds;
     auto regionLabels = regionStorage && !regionStorage->labels.empty() ? regionStorage->labels : fallbackLabels;
@@ -289,10 +293,13 @@ namespace anm2ed::imgui::wizard
       if (isFlipXSet) frameChange.isFlipX = std::make_optional(isFlipX);
       if (isFlipYSet) frameChange.isFlipY = std::make_optional(isFlipY);
 
-      DOCUMENT_EDIT(document, localize.get(EDIT_CHANGE_FRAME_PROPERTIES), Document::FRAMES,
-                    document.item_get()->frames_change(frameChange, itemType, changeType, frames));
+      if (auto item = document.item_get())
+      {
+        DOCUMENT_EDIT(document, localize.get(EDIT_CHANGE_FRAME_PROPERTIES), Document::FRAMES,
+                      item->frames_change(frameChange, itemType, changeType, frames));
 
-      isChanged = true;
+        isChanged = true;
+      }
     };
 
     ImGui::Separator();
diff --git a/src/imgui/wizard/generate_animation_from_grid.cpp b/src/imgui/wizard/generate_animation_from_grid.cpp
index 3c9ba64..6d8bec2 100644
--- a/src/imgui/wizard/generate_animation_from_grid.cpp
+++ b/src/imgui/wizard/generate_animation_from_grid.cpp
@@ -57,21 +57,27 @@ namespace anm2ed::imgui::wizard
 
       if (document.reference.itemType == anm2::LAYER)
       {
-        auto& texture =
-            document.anm2.content.spritesheets[document.anm2.content.layers[document.reference.itemID].spritesheetID]
-                .texture;
+        auto layerIt = document.anm2.content.layers.find(document.reference.itemID);
+        if (layerIt != document.anm2.content.layers.end())
+        {
+          auto spritesheetIt = document.anm2.content.spritesheets.find(layerIt->second.spritesheetID);
+          if (spritesheetIt != document.anm2.content.spritesheets.end())
+          {
+            auto& texture = spritesheetIt->second.texture;
 
-        auto index = std::clamp((int)(time * (count - 1)), 0, (count - 1));
-        auto row = index / columns;
-        auto column = index % columns;
-        auto crop = startPosition + ivec2(size.x * column, size.y * row);
-        auto uvMin = (vec2(crop) + vec2(0.5f)) / vec2(texture.size);
-        auto uvMax = (vec2(crop) + vec2(size) - vec2(0.5f)) / vec2(texture.size);
+            auto index = std::clamp((int)(time * (count - 1)), 0, (count - 1));
+            auto row = index / columns;
+            auto column = index % columns;
+            auto crop = startPosition + ivec2(size.x * column, size.y * row);
+            auto uvMin = (vec2(crop) + vec2(0.5f)) / vec2(texture.size);
+            auto uvMax = (vec2(crop) + vec2(size) - vec2(0.5f)) / vec2(texture.size);
 
-        mat4 transform = transform_get(zoom) * math::quad_model_get(size, {}, pivot);
+            mat4 transform = transform_get(zoom) * math::quad_model_get(size, {}, pivot);
 
-        texture_render(shaderTexture, texture.id, transform, vec4(1.0f), {},
-                       math::uv_vertices_get(uvMin, uvMax).data());
+            texture_render(shaderTexture, texture.id, transform, vec4(1.0f), {},
+                           math::uv_vertices_get(uvMin, uvMax).data());
+          }
+        }
       }
 
       unbind();
@@ -112,4 +118,4 @@ namespace anm2ed::imgui::wizard
 
     if (ImGui::Button(localize.get(BASIC_CANCEL), widgetSize)) isEnd = true;
   }
-}
\ No newline at end of file
+}
diff --git a/src/manager.cpp b/src/manager.cpp
index 3a4a41a..0886b9a 100644
--- a/src/manager.cpp
+++ b/src/manager.cpp
@@ -199,8 +199,10 @@ namespace anm2ed
     {
       if (id == -1)
         editLayer = anm2::Layer();
+      else if (auto it = document->anm2.content.layers.find(id); it != document->anm2.content.layers.end())
+        editLayer = it->second;
       else
-        editLayer = document->anm2.content.layers.at(id);
+        return;
 
       document->layer.reference = id;
 
@@ -224,8 +226,10 @@ namespace anm2ed
     {
       if (id == -1)
         editNull = anm2::Null();
+      else if (auto it = document->anm2.content.nulls.find(id); it != document->anm2.content.nulls.end())
+        editNull = it->second;
       else
-        editNull = document->anm2.content.nulls.at(id);
+        return;
 
       document->null.reference = id;
 
diff --git a/src/socket.cpp b/src/socket.cpp
index 33025c3..d35c753 100644
--- a/src/socket.cpp
+++ b/src/socket.cpp
@@ -1,6 +1,7 @@
 #include "socket.hpp"
 
 #include <cerrno>
+#include <climits>
 
 namespace anm2ed
 {
@@ -203,7 +204,12 @@ namespace anm2ed
 
     while (totalSent < size)
     {
-      auto sent = ::send(handle, bytes + totalSent, static_cast<int>(size - totalSent), 0);
+      auto chunkSize = static_cast<int>(std::min<size_t>(size - totalSent, static_cast<size_t>(INT_MAX)));
+#ifdef MSG_NOSIGNAL
+      auto sent = ::send(handle, bytes + totalSent, chunkSize, MSG_NOSIGNAL);
+#else
+      auto sent = ::send(handle, bytes + totalSent, chunkSize, 0);
+#endif
       if (sent <= 0)
       {
         lastError = socket_last_error();
@@ -229,7 +235,8 @@ namespace anm2ed
 
     while (totalReceived < size)
     {
-      auto received = ::recv(handle, bytes + totalReceived, static_cast<int>(size - totalReceived), 0);
+      auto chunkSize = static_cast<int>(std::min<size_t>(size - totalReceived, static_cast<size_t>(INT_MAX)));
+      auto received = ::recv(handle, bytes + totalReceived, chunkSize, 0);
       if (received <= 0)
       {
         lastError = socket_last_error();
diff --git a/workshop/metadata.xml b/workshop/metadata.xml
index 4904701..2b36552 100644
--- a/workshop/metadata.xml
+++ b/workshop/metadata.xml
@@ -53,6 +53,6 @@ Alternatively, if you have subscribed to the mod, you can find the latest releas
 [h3]Happy animating![/h3]
 [img]https://files.catbox.moe/4auc1c.gif[/img]
 </description>
-    <version>2.16</version>
+    <version>2.17</version>
     <visibility>Public</visibility>
 </metadata>