Optimize discussion list

Author: jcc

resources/views/discussion/index.blade.php

@@ -16,7 +16,7 @@
                 <div class="media my-3">
                     <div class="media-left mr-3">
                         <a href="{{ url('discussion', ['id' => $discussion->id]) }}">
-                            <img class="media-object rounded-circle" width="50" src="{{ $discussion->user->avatar }}">
+                            <img class="media-object rounded-circle" width="50" src="{{ $discussion->user->avatar ?? config('blog.default_avatar') }}">
                         </a>
                     </div>
                     <div class="media-body">