I used to use entr extensively for Sketch plugin development (the vector editing tool by Bohemian Coding). However the app used to crash randomly and I felt my plugin was causing it. I spent an inordinate amount of time trying to debug it, replacing libraries, changing code and so on. Thankfully I noticed at some point that the app was behaving well for long durations of time when I started it without entr. I got rid of it from my toolchain and things have been well ever since.

I still don't know the root cause, but now I know one more place to look for heisenbugs.