I'm seeing crashes with 31.0.50.
I'm doing exactly the same activities that I did with 31.0.46 which never crashed.
First persistent crash happened yesterday and was (I thought) caused by me trying to tag some M4A audio. I've had problems with that format before so instead of reporting the problem I transcoded the files to mp3 and the problem seemed to go away.
Then today when trying to tag some jpgs MC crashed. When I restarted MC and checked for any database corruption by running auto-import, MC again crashed when trying to read the jpgs, which MC thought had changed because it crashed before changes from previous sessions were saved. Log attached for this crash.
I then deleted the jpgs, restarted MC, and re-ran auto-import. MC reported the missing jpgs as expected but did not crash.
I suppose this could be caused by a bad jpg but I've never seen this problem before and have tagged many thousands of jpgs.