Seen on an unrelated patch
https://gerrit.wikimedia.org/r/c/mediawiki/extensions/Linter/+/1078749
https://integration.wikimedia.org/ci/job/mwext-php74-phan/46699/console
15:38:49 includes/SpecialLintErrors.php:213 PhanTypeMismatchArgumentNullableInternal Argument 1 ($string) is $namespaceRequestValues of type ?string but \strlen() takes string (expected type to be non-nullable) 15:38:49 includes/SpecialLintErrors.php:214 PhanTypeMismatchArgumentNullableInternal Argument 2 ($string) is $namespaceRequestValues of type ?string but \explode() takes string (expected type to be non-nullable)
Seemingly broken by rMW7be5a303d162: WebRequest: Add PHP return type hint for getRawVal