Fix Nullable exception

Author: tito10047

Diff for: src/Twig/Components/DashboardImportance.php

@@ -36,6 +36,9 @@ public function getMaxImportance(): array
         $maxImportance = Importance::min();
         $maxNotifier = null;
         foreach ($projects as [$importance, $notifier]) {
+            if (!$importance) {
+                continue;
+            }
             if ($importance->isHigherThan($maxImportance)) {
                 $maxImportance = $importance;
                 $maxNotifier = $notifier;