Prevent animator events from calling SendCustomEvent on proxies

- Now check the calling method to see if it's a native call which indicates Unity is calling the code and block the call. Resolves #58

Assets/UdonSharp/Scripts/UdonSharpBehaviour.cs

@@ -3,7 +3,11 @@
 using System.Reflection;
 using UnityEngine;
 using VRC.Udon.Common.Interfaces;
+
+#if UNITY_EDITOR
+using System.Diagnostics;
 using VRC.Udon.Serialization.OdinSerializer;
+#endif
 
 namespace UdonSharp
 {
@@ -35,6 +39,17 @@ public void SetProgramVariable(string name, object value)
 
         public void SendCustomEvent(string eventName)
         {
+#if UNITY_EDITOR
+            if (_backingUdonBehaviour != null) // If this is a proxy, we need to check if this is a valid call to SendCustomEvent, since animation events can call it when they shouldn't
+            {
+                StackFrame frame = new StackFrame(1); // Get the frame of the calling method
+
+                // If the calling method is null, this has been called from native code which indicates it was called by Unity, which we don't want on proxies
+                if (frame.GetMethod() == null)
+                    return;
+            }
+#endif
+
             MethodInfo eventmethod = GetType().GetMethods(BindingFlags.Public | BindingFlags.Instance).Where(e => e.Name == eventName && e.GetParameters().Length == 0).FirstOrDefault();
 
             if (eventmethod != null)