FX: Fix copy is not a function error

hrt/prefab/fx/BaseFX.hx

@@ -234,7 +234,9 @@ class BaseFXTools {
 	}
 
 	public static function makeRendererFXParams(rfxElt: hrt.prefab.rfx.RendererFX) {
-		var serializedProps : Array<Dynamic> = @:privateAccess Prefab.getSerializablePropsForClass(Type.getClass(cast rfxElt)).copy();
+		var classRfx = Type.getClass(cast rfxElt);
+		var originalProps : Array<Dynamic> = @:privateAccess Prefab.getSerializablePropsForClass(classRfx);
+		var serializedProps : Array<Dynamic> = originalProps.copy();
 		var ret : Array<{field : hrt.prefab.Prefab.PrefabField, value : Value}> = null;
 		for (f in serializedProps) {
 			if (!(Reflect.field(rfxElt, f.name) is Float))