Return default user avatar if not set

app/users/routes.py

@@ -65,7 +65,7 @@ def user(user_id):
 def profile_avatar(user_id):
     user = User.query.get_or_404(user_id)
     if user.avatar is None:
-        abort(404)
+        return redirect(url_for('static', filename='images/default_avatar.png'))
     if not user.is_public and not (user == current_user or current_user.is_administrator()):
         abort(403)
     return send_from_directory(