Steps to replicate the issue (include links if applicable):

• I noticed a flood of errors in thumbor https://logstash.wikimedia.org/goto/0aa3ec49602595910f0b490dedd037dc

What happens?:
Thousands upon thousands of CSS parsing error\n" statements are logged to the error log. This might be a librsvg issue, which as far as I know should be the only place that has CSS. Possibly a very big file has thousands of invalid CSS statements, or it could be that some sort of recursion is occurring.

I tried identifying the source that triggered this, but was not able to do so.

What should have happened instead?:
Either these errors should have been ignored, or condensed with a counter, but this is a bit ridiculous.

It should also be possible to identify which file caused this, but that was almost impossible. T337677 might have helped here.

Software version (skip for WMF-hosted wikis like Wikipedia):

Other information (browser name/version, screenshots, etc.):