Adjust retry error region-tags for docs migration (#615)

* Adjust retry error tags

* Unify hello-world error region-tags

* Further error sample unification

* Clarify comments + add HTTP sample

* Move region tags inside functions

* Fix typo

* s/Errors/Error Reporting/

functions/helloworld/index.js

@@ -125,47 +125,68 @@ exports.helloGCSGeneric = (event, callback) => {
 };
 // [END functions_helloworld_storage_generic]
 
-// [START functions_helloworld_error]
 /**
  * Background Cloud Function that throws an error.
  *
  * @param {object} event The Cloud Functions event.
  * @param {function} callback The callback function.
  */
+
 exports.helloError = (event, callback) => {
-  // This WILL be reported to Stackdriver Error Reporting
-  throw new Error('I failed you');
+  // [START functions_helloworld_error]
+  // These WILL be reported to Stackdriver Error Reporting
+  console.error(new Error('I failed you'));
+  throw new Error('I failed you'); // Will cause a cold start if not caught
+
+  // [END functions_helloworld_error]
 };
-// [END functions_helloworld_error]
 
-/* eslint-disable */
-// [START functions_helloworld_error_2]
 /**
  * Background Cloud Function that throws a value.
  *
  * @param {object} event The Cloud Functions event.
  * @param {function} callback The callback function.
  */
+/* eslint-disable no-throw-literal */
+
 exports.helloError2 = (event, callback) => {
-  // This will NOT be reported to Stackdriver Error Reporting
-  throw 1;
+  // [START functions_helloworld_error]
+  // These will NOT be reported to Stackdriver Error Reporting
+  console.info(new Error('I failed you')); // Logging an Error object at the info level
+  console.error('I failed you'); // Logging something other than an Error object
+  throw 1; // Throwing something other than an Error object
+  // [END functions_helloworld_error]
 };
-// [END functions_helloworld_error_2]
+/* eslint-enable no-throw-literal */
 
-// [START functions_helloworld_error_3]
 /**
- * Background Cloud Function that throws an error.
+ * Background Cloud Function that returns an error.
  *
  * @param {object} event The Cloud Functions event.
  * @param {function} callback The callback function.
  */
+/* eslint-disable */
 exports.helloError3 = (event, callback) => {
-  // This will NOT be reported to Stackdriver errors
+  // This will NOT be reported to Stackdriver Error Reporting
+  // [START functions_helloworld_error]
   callback('I failed you');
+  // [END functions_helloworld_error]
 };
-// [END functions_helloworld_error_3]
 /* eslint-enable */
 
+/**
+ * HTTP Cloud Function that returns an error.
+ *
+ * @param {Object} req Cloud Function request context.
+ * @param {Object} res Cloud Function response context.
+ */
+exports.helloError4 = (req, res) => {
+  // This will NOT be reported to Stackdriver Error Reporting
+  // [START functions_helloworld_error]
+  res.status(500).send('I failed you');
+  // [END functions_helloworld_error]
+};
+
 // [START functions_helloworld_template]
 const path = require('path');
 const pug = require('pug');