Merge pull request #41 from pietro-lopes/1.20/dev

Fixed some general concurrency issue

common/src/main/java/dev/latvian/mods/rhino/ArrowFunction.java

@@ -37,7 +37,7 @@ public ArrowFunction(Context cx, Scriptable scope, Callable targetFunction, Scri
 	}
 
 	@Override
-	public Object call(Context cx, Scriptable scope, Scriptable thisObj, Object[] args) {
+	public synchronized Object call(Context cx, Scriptable scope, Scriptable thisObj, Object[] args) {
 		Scriptable callThis = boundThis != null ? boundThis : ScriptRuntime.getTopCallScope(cx);
 		return targetFunction.call(cx, scope, callThis, args);
 	}