🐛 Fix None default role in user installed apps.

Author: Paillat-dev

discord/member.py

@@ -566,7 +566,8 @@ def roles(self) -> list[Role]:
             role = g.get_role(role_id)
             if role:
                 result.append(role)
-        result.append(g.default_role)
+        if g.default_role:
+            result.append(g.default_role)
         result.sort()
         return result