Custom linter: Let custom linter run all checks even if the check before failed.

[Fuzzy2319]

Group all the error messages in one pass instead of printing them one at a time.

[LynxDev2]

Doesn’t this already happen?

[MonsterDruide1]

Not on all checks. When starting to work on the custom linter, I intended it to only output one error at a time, to avoid false positives due to the logic being thrown off by the first reported error, but ... some checks are more robust and can recover after a failure, so it's pretty inconsistent at the moment. Some checks immediately stop after finding a single faulty instance, some continue within the same file.