bug#39977: 28.0.50; Unhelpful stack trace

[martin rudalics]

> I haven't understood the sequence of events which causes leads to this
> crash case.  I'm a little embarrased to reveal it but I can try to
> pass on the recipe to Martin.

Do you ever evaluate something that could cause a frame deletion when
setting a mode or header-line string or a frame title.  Do you use the
tab-bar?  Where in your code does the "quitting the window (and frame)"
you mentioned earlier happen?

martin