TopEditsController: prevent null namespace (#606)

Author: agoujot

src/Controller/TopEditsController.php

@@ -94,7 +94,7 @@ public function setUpTopEdits( TopEditsRepository $topEditsRepo, AutomatedEditsH
 			$this->project,
 			$this->user,
 			$this->page,
-			$this->namespace,
+			$this->namespace ?? 'all',
 			$this->start,
 			$this->end,
 			$this->limit,