return 404 when user cannot be found

yellow/routes.py

@@ -75,10 +75,13 @@ async def user_page(name: str):
     if not name or len(name) <= 1:
         raise Exception("invalid name")
 
-    _user = User.select().where(
-        User.username == name,
-        User.address.is_null(False)
-    ).get()
+    try:
+        _user = User.select().where(
+            User.username == name,
+            User.address.is_null(False)
+        ).get()
+    except:
+        return abort(404)
 
     return await render_template('user.html', users=[_user])