fix for empty sounds/animation collections

src/resource/xml/animation_entry.cpp

@@ -4,8 +4,9 @@
 
 namespace game::resource::xml
 {
-  const std::string& AnimationEntryCollection::get()
+  std::string* AnimationEntryCollection::get()
   {
-    return at(util::vector::random_index_weighted(*this, [](const auto& entry) { return entry.weight; })).animation;
+    if (empty()) return nullptr;
+    return &at(util::vector::random_index_weighted(*this, [](const auto& entry) { return entry.weight; })).animation;
   }
 }

src/resource/xml/animation_entry.hpp

@@ -17,7 +17,7 @@ namespace game::resource::xml
   class AnimationEntryCollection : public std::vector<AnimationEntry>
   {
   public:
-    const std::string& get();
+    std::string* get();
   };
 
 }

src/resource/xml/sound_entry.cpp

@@ -4,13 +4,15 @@
 
 namespace game::resource::xml
 {
-  Audio& SoundEntryCollection::get()
+  Audio* SoundEntryCollection::get()
   {
-    return at(util::vector::random_index_weighted(*this, [](const auto& entry) { return entry.weight; })).sound;
+    if (empty()) return nullptr;
+    return &at(util::vector::random_index_weighted(*this, [](const auto& entry) { return entry.weight; })).sound;
   }
 
   void SoundEntryCollection::play()
   {
-    at(util::vector::random_index_weighted(*this, [](const auto& entry) { return entry.weight; })).play();
+    if (empty()) return;
+    if (auto audio = get()) audio->play();
   }
 }

src/resource/xml/sound_entry.hpp

@@ -18,7 +18,7 @@ namespace game::resource::xml
   class SoundEntryCollection : public std::vector<SoundEntry>
   {
   public:
-    Audio& get();
+    Audio* get();
     void play();
   };
 }