I came across this invalid sizing option in the wild: (number)px(number)px. Valid options are:
The file specification in question has an unnamed caption parameter, which is interpreted correctly, so it looks like the "px" parameter is being read as a sizing parameter, but it is invalid and is not processed. If I change it to "500p", it is correctly flagged by Linter as extra text.
"500px500px" should be flagged as a Bogus file option by Linter.