Update QueryCollector.php fix issue #1775 (#1776)

Test for null value in strpos in QueryCollector.php to solve laravel-debugbar issue #1775 and snipe-it issue 16476.

Author: Mathias-DS

src/DataCollector/QueryCollector.php

@@ -378,7 +378,7 @@ protected function findMiddlewareFromFile($file)
         $filename = pathinfo($file, PATHINFO_FILENAME);
 
         foreach ($this->middleware as $alias => $class) {
-            if (strpos($class, $filename) !== false) {
+            if (!is_null($class) && !is_null($filename) && strpos($class, $filename) !== false) {
                 return $alias;
             }
         }