Added casting to array. If this is missing it can happen that the returned value is null.

Classes/ViewHelpers/ProgressViewHelper.php

@@ -57,7 +57,7 @@ class ProgressViewHelper extends AbstractViewHelper
         //handling famous off by one
         $activeStep -= $offset;
         //make sure our array index is numeric
-        $links = \array_values($links);
+        $links = \array_values((array)$links);
         if (!$linkCount) {
             $linkCount = \count($links);
         }