Tweak eslint config

One of the most common CI failures seems to be "Error: Device or resource busy" when printing out the linter report from eslint.

This improves the eslint configuration file so that there are fewer false positives, and also fixes some errors that wouldn't prevent getting good output from git blame (which is why I haven't just fixed them all at once.)

My theory is that a smaller report file will help the problem. I don't know if it worked, but a good sign is that the eslint job passed on the first try, whereas usually it fails 5 or more times first!