That's the point and symptom of this crash/ test though, the crash oftentimes disappears (or gets delayed to some other moment) when you change something in the code or a level.

Btw. that line of coding, i.e. waiting for level_load to finish, does not change anything as the function only resumes after level_load has been completed. Only in old WDL or old C-Script times level_load was executed one frame later/ at the end of the frame, thus you needed to wait there.