logger.warn does not exist

server/index.js

@@ -91,7 +91,7 @@ if (process.env.NODE_ENV === 'development') {
     app.on('error', (error, ctx) => {
       // we don't need to report every time a request stops to the bug tracker
       if (error.code === 'EPIPE' || error.code === 'ECONNRESET') {
-        logger.warn('Connection error', { error });
+        console.warn('Connection error', { error });
       } else {
         bugsnag.koaHandler(error, ctx);
       }