Wikimedia Bugzilla is closed!

If you set your wiki to display warnings, visiting a non-existent schema page (on the machine that holds the schemas for event logging) triggers

  Warning: Invalid message parameter: a:1:{s:3:"raw";N;} in .../includes/Message.php on line 625

This is coming from the onBeforePageDisplay code in JsonSchemaHooks.php to show the subtitle "Revision nnnn":

            $out->addSubtitle( $out->msg( 'eventlogging-revision-id' )
                // We use 'rawParams' rather than 'numParams' to make it
                // easy to copy/paste the value into code.
                ->rawParams( $out->getRevisionId() )
The Schema page ends up displaying "Revision [INVALID]", which is fine, but the message parsing code is unhappy when the getRevisionId() is NULL (bug?!)

The stack in Message.php is 
  extractParam()
  replaceParameters()
  toString()
  escaped()

The simplest fix is to cast the revision ID to an integer in JsonSchemaHooks.php line 106:
                ->rawParams( (integer) $out->getRevisionId() )
which results in displaying "Revision 0" on a new schema page.