Using 2020r2.1, I find that Xojo will often (but not always) throw a fatal error, if I add or remove breakpoints during a run. In my experience, this seems to be recent behavior.
For instance, I might have a breakpoint (in a loop, for instance), and remove it after seeing what I want to see. Alternately, I might decide to add a breakpoint further down in the same method.
Either one MIGHT cause the crash. Fortunately, Xojo gives me the chance to save my work before it dies.
The workaround is a variation of the old Henny Youngman joke: I said to the doctor (making random gesture) ‘it hurts when I do that’—he said ‘don’t do that’.
I have browsed Feedback just a bit and haven’t found precisely this. Before filing my own case, I want to examine this a little more, to see if something in particular will make it reproducible.
But I’ll start with this question: has anyone else seen this?