No clear indicator if a file was not found/failed to load

[DeStilleGast]

Basicly what the titles says, I noticed that a sample/demo song in bassoon was taking ages to load.
after inspection I found out that the file did not exist on my local server,

trying to load as example: "62-channels: forever young xm", the loading indicator shows and stays there until you load a file that does exist but in the console you can see that the server returned a 404 but gets overshadowed by a wall from a exception that tells me that variable a is undefined