Fix #1141 referencing DI element when not initialized

admin.php

@@ -523,18 +523,17 @@ class AdminPlugin extends Plugin
      */
     public function onShutdown()
     {
-        // Just so we know that we're in this debug mode
+        if ($this->active) {
+            //only activate when Admin is active
+            if ($this->shouldLoadAdditionalFilesInBackground()) {
+                $this->loadAdditionalFilesInBackground();
+            }
+        } else {
+            //if popularity is enabled, track non-admin hits
             if ($this->config->get('plugins.admin.popularity.enabled')) {
-
-            // Only track non-admin
-            if (!$this->active) {
                 $this->popularity->trackHit();
             }
         }
-
-        if ($this->grav['admin']->shouldLoadAdditionalFilesInBackground()) {
-            $this->grav['admin']->loadAdditionalFilesInBackground();
-        }
     }
 
     /**