*Popup Pessage* Window Hangs and Can't be Killed

[veqqq]

After compiling a whole file (C-c C-k) with multiple errors, at least one popup window will remain. Selecting it, you can modify the text, but C-x k to Kill buffer: (Popup Message) results in a "buffer does not exist". C-x b names it editor error but trying to kill it has the same result.

I'm not sure of the best way to address it yet, but suspect the same fix might remove C-x C-e results which linger after the function was removed. I've not explored the code base much yet.