check for blueprints method

CHANGELOG.md

@@ -5,6 +5,8 @@
     * Added custom object support for filepicker field
     * Don't allow saving of a user with no local account file
     * Controls for `list` field were not in sync between top and bottom
+1. [](#bugfix)
+    * Check    
 
 # v1.8.1
 ## 05/15/2018

admin.php

@@ -762,7 +762,8 @@ class AdminPlugin extends Plugin
     {
         // Special case to redirect after changing the admin route to avoid 'breaking'
         $obj = $event['object'];
-        if (null !== $obj) {
+
+        if (null !== $obj && method_exists($obj, 'blueprints')) {
             $blueprint = $obj->blueprints()->getFilename();
 
             if ($blueprint === 'admin/blueprints' && isset($obj->route) && $this->admin_route !== $obj->route) {