Don't block backend connection when a plugin migration triggers exception (#3188)

modules/backend/controllers/Auth.php

@@ -85,8 +85,13 @@ class Auth extends Controller
             'password' => post('password')
         ], $remember);
 
+        try {
             // Load version updates
             UpdateManager::instance()->update();
+        }
+        catch (Exception $ex) {
+            Flash::error($ex->getMessage());
+        }
 
         // Log the sign in event
         AccessLog::add($user);