- Firing on key up is weird. Generally you should do actions on key down unless you have some visual feedback while a key is held.
- The fireball likes to destroy itself right after spawning. It might be responding to the player collision.
- Input direction is being mapped to a world space, but most players find it more natural for input to be mapped based on the camera orientation.
- There is no indication that the player needs to press a button to change scenes.
- I could not progress further at a point when sceneChangeScript::Update started throwing null reference exceptions. Unity is kind and catches managed exceptions for you but I still do not recommend letting them go uncaught (this will crash on certain builds). In general I recommend being careful about checking for null before dereferencing things unless you have a compelling reason not to.
- While I can't see what null reference was causing the exception, the static Animation component reference is highly suspicious. It is possible that the component was destroyed and then the reference was technically still pointing to a now invalided object, which Unity's strange comparison overloading will make it throw exceptions as if it were null. Static is a thing best avoided, but if you wish to have a static reference to a Unity Object, ensure that you set the reference back to null properly from the OnDestroy function unless you want a memory leak and possibly spooky shenanigans when using interfaces and events.