lil dialogue fix

if u had another dialogue starting in the callback, in the new script Dialogue.cutscene would be always null

Author: NexIsDumb

source/funkin/game/cutscenes/DialogueCutscene.hx

@@ -197,7 +197,7 @@ class DialogueCutscene extends Cutscene {
 		dialogueScript.destroy();
 
 		super.destroy();
-		cutscene = null;
+		if (cutscene == this) cutscene = null;
 		FlxG.cameras.remove(dialogueCamera);
 	}
 }