The crashes are spurious, and they occur in different places in libmutter.so, but I’m attaching a Gist with a stack trace from journalctl.
I’m running Wayland, which is most likely relevant. This mostly happens when I’m developing my app, where I often have to close its window, recompile, and run it again, but it sometimes happens with other programs too. I could switch to X11 but I don’t know how to make Mutter run in 144 fps to match my monitor’s refresh rate, otherwise the animations all look very stuttery.
If someone could point me towards how to debug these crashes, or, at the very least, get a proper stack trace with line information, please let me know.