Fixed the "insivible wall" bug

First of all, sorry for the issue. It had only happenned to me once and I tought it only affected a latter enemy (which was already fixed before release).

A few users reported a bug where the player would get stuck on an invisible obstacle. I looked into it and believe it was caused by one of Game Maker's movement functions. This project is using an old version of the engine, so said function might be bugged. The function was supposed to move towards a point while avoiding target, but seems to register some defeated enemies as obstacles despite them getting deleted after dying. This system has been replaced with the player stopping if they touch one of the walls. I have tested the second stage where the bug took place, defeated all enemies and nothing strange has happenned.

Thanks for your patience.