I was working on a blueprint and used the ForEachLoop macro inside a function that has a local variable. This caused a crash that has already been reported in another AnswerHub post (Adding For Each Loop to Blueprint function containing local variables causes crash - Blueprint - Unreal Engine Forums). I had not saved the blueprint yet, but there was an autosave, so UE4 restored the autosave when I restarted the editor.
However, the blueprint seemed to be corrupt from that point forward, because even after removing all the functionality in the blueprint and leaving a test print, the blueprint would compile, but it would immediately crash the editor when I ran Simulate or Play.
I’m not sure if this is the right way to repro the bug but the editor doesn’t seem to verify the blueprint for integrity.