fix(api): duplicate reply on error in /daily-coding-challenge-completed (#60999)

api/src/routes/protected/challenge.ts

@@ -291,6 +291,7 @@ export const challengeRoutes: FastifyPluginCallbackTypebox = (
             type: 'error',
             message: 'That does not appear to be a valid challenge submission.'
           });
+        } else {
           fastify.errorHandler(error, req, reply);
         }
       }