Crash in completion popover
With Builder 3.40.0-141-g68b24d8b4+ (gnome-nightly flatpak), happened today three times to me (the third time I had prepared a gdb to get the backtrace :).
Sometimes when working on C files (no idea if that's particularly useful to know) Builder suddently crashed while I had moved the cursor to a new place in the text. The backtrace seems to indicate it's indeed related to the completion popover. I have a gdb core-file available if that can somehow help (not sure how they work but it helped me get the backtrace back with full debug symbols afterwards).