regex format checker crashes with RecursionError on deeply nested patterns #1538

The regex format checker is registered with raises=re.error, but re.compile raises RecursionError (not an re.error subclass) when the pattern nesting exceeds the C stack limit. This causes an uncaught exception to propagate from the validator instead of reporting the instance as invalid.

Reproduction

from jsonschema import Draft202012Validator, FormatChecker

v = Draft202012Validator({"format": "regex"}, format_checker=FormatChecker())
list(v.iter_errors("(" * 500))
# RecursionError: maximum recursion depth exceeded

Expected

The instance should be reported as invalid (not a valid regex), not raise.

Cause

re.compile("(" * 500) raises RecursionError, which is not a subclass of re.error, so FormatChecker.check does not convert it into a FormatError.

This is the same class of issue as the OverflowError case in #1526, but a distinct exception type.

Versions

• jsonschema 4.26.0
• Python 3.13