Prevent premature unload when DllManipulatorScript is duplicated

Author: mcpiroman

scripts/DllManipulatorScript.cs

@@ -86,13 +86,16 @@ private void OnEnable()
 
         private void OnDestroy()
         {
-            //Note on threading: Because we don't wait for other threads to finish, we might be stealing function delegates from under their nose if Unity doesn't happen to close them yet.
-            //On Preloaded mode this leads to NullReferenceException, but on Lazy mode the DLL and function would be just reloaded so we would up with loaded DLL after game exit.
-            //Thankfully thread safety with Lazy mode is not implemented yet.
+            if (_singletonInstance == this)
+            {
+                //Note on threading: Because we don't wait for other threads to finish, we might be stealing function delegates from under their nose if Unity doesn't happen to close them yet.
+                //On Preloaded mode this leads to NullReferenceException, but on Lazy mode the DLL and function would be just reloaded so we would up with loaded DLL after game exit.
+                //Thankfully thread safety with Lazy mode is not implemented yet.
 
-            DllManipulator.UnloadAll();
-            DllManipulator.ForgetAllDlls();
-            DllManipulator.ClearCrashLogs();
+                DllManipulator.UnloadAll();
+                DllManipulator.ForgetAllDlls();
+                DllManipulator.ClearCrashLogs();
+            }
         }
     }
 }