...

resources/views/layouts/site.blade.php

@@ -37,9 +37,9 @@
   <meta name="msapplication-TileColor" content="#3daee9">
   <meta name="msapplication-TileImage" content="/ms-icon-144x144.png">
   <meta name="theme-color" content="#3daee9">
-  @if (isset($user) && $user->profile->gender == 1)
+  @if (isset($user) && isset($user->profile) && $user->profile->gender == 1)
   <link href="{{ asset('css/app_m.css') }}" rel="stylesheet">
-  @elseif (isset($user) && $user->profile->gender == 2)
+  @elseif (isset($user) && isset($user->profile) && $user->profile->gender == 2)
   <link href="{{ asset('css/app_f.css') }}" rel="stylesheet">
   @else
   <link href="{{ asset('css/app.css') }}" rel="stylesheet">