Update error logging example (#930)

Author: Mytrill

functions/helloworld/index.js

@@ -147,6 +147,7 @@ exports.helloError = (event, callback) => {
   // [START functions_helloworld_error]
   // These WILL be reported to Stackdriver Error Reporting
   console.error(new Error('I failed you'));
+  console.error('I failed you', new Error('I failed you too'));
   throw new Error('I failed you'); // Will cause a cold start if not caught
 
   // [END functions_helloworld_error]