No non-standard characters in my password. Just alphanumeric.
Tried a new password and it still crashed.

I did more testing, and I think I've found the problem: the bug lies in the "Label Sync" plugin.

I did this in steps:

I restored from seed and I shut down Electrum, without it crashing on startup.
I added an API key for the Label Sync plugin, but I didn't check the "turn on" checkmark, I shut it down without Electrum crashing on startup.
I checked the checkmark for turning on Label Sync and shut down the client, and then Electrum will crash on startup repeatedly.

I hope that helps making this bug dead.