Fix type checking for new jsonschema annotations

One fix is a `type:ignore` comment for a bad annotation which was
introduced and then fixed. The other is the addition of an `if` check
for an optional list which was being treated as non-optional.

Author: sirosen

src/check_jsonschema/formats.py

@@ -50,12 +50,17 @@ def make_format_checker(
     formats.remove("regex")
     checker = jsonschema.FormatChecker(formats=formats)
 
+    # FIXME: type-ignore comments to handle incorrect annotation
+    # fixed in https://github.com/python/typeshed/pull/7990
+    # once available, remove the ignores
     if opts.regex_behavior == RegexFormatBehavior.disabled:
         pass
     elif opts.regex_behavior == RegexFormatBehavior.default:
-        checker.checks("regex", raises=re.error)(_gated_regex_check)
+        checker.checks("regex", raises=re.error)(  # type: ignore[arg-type]
+            _gated_regex_check
+        )
     elif opts.regex_behavior == RegexFormatBehavior.python:
-        checker.checks("regex", raises=re.error)(_regex_check)
+        checker.checks("regex", raises=re.error)(_regex_check)  # type: ignore[arg-type]
     else:  # pragma: no cover
         raise NotImplementedError
 

src/check_jsonschema/utils.py

@@ -118,6 +118,7 @@ def print_error(err: Exception, mode: str = "short") -> None:
 def iter_validation_error(
     err: jsonschema.ValidationError,
 ) -> t.Iterator[jsonschema.ValidationError]:
-    for e in err.context:
-        yield e
-        yield from iter_validation_error(e)
+    if err.context:
+        for e in err.context:
+            yield e
+            yield from iter_validation_error(e)