Fix crash in animations system when assets gets loading/unloaded while async jobs are active

#2974

Source/Engine/Content/Assets/AnimationGraph.cpp

@@ -10,6 +10,7 @@
 #include "Engine/Serialization/MemoryReadStream.h"
 #include "Engine/Serialization/MemoryWriteStream.h"
 #include "Engine/Content/Factories/BinaryAssetFactory.h"
+#include "Engine/Animations/Animations.h"
 #include "Engine/Threading/Threading.h"
 #include "Engine/Debug/Exceptions/ArgumentNullException.h"
 
@@ -24,6 +25,8 @@ AnimationGraph::AnimationGraph(const SpawnParams& params, const AssetInfo* info)
 
 Asset::LoadResult AnimationGraph::load()
 {
+    ConcurrentSystemLocker::WriteScope systemScope(Animations::SystemLocker);
+
     // Get stream with graph data
     const auto surfaceChunk = GetChunk(0);
     if (surfaceChunk == nullptr)
@@ -48,6 +51,7 @@ Asset::LoadResult AnimationGraph::load()
 
 void AnimationGraph::unload(bool isReloading)
 {
+    ConcurrentSystemLocker::WriteScope systemScope(Animations::SystemLocker);
     Graph.Clear();
 }
 
@@ -79,6 +83,7 @@ bool AnimationGraph::InitAsAnimation(SkinnedModel* baseModel, Animation* anim, b
         Log::ArgumentNullException();
         return true;
     }
+    ConcurrentSystemLocker::WriteScope systemScope(Animations::SystemLocker);
 
     // Create Graph data
     MemoryWriteStream writeStream(512);
@@ -172,7 +177,7 @@ bool AnimationGraph::SaveSurface(BytesContainer& data)
         LOG(Error, "Asset loading failed. Cannot save it.");
         return true;
     }
-
+    ConcurrentSystemLocker::WriteScope systemScope(Animations::SystemLocker);
     ScopeLock lock(Locker);
 
     if (IsVirtual())