add hint text

common.js

@@ -73,6 +73,10 @@ function inputError(message) {
   printErrorAndExit(message, 'Input Error:');
 }
 
+function printErrorWithHintAndExit(message, hint, prefix) {
+  printErrorAndExit(message + '\n\n{bold}{yellow}Hint:{/yellow}{/bold} ' + hint, prefix);
+}
+
 function printErrorAndExit(message, prefix) {
   if (!prefix) {
     prefix = 'Error:';
@@ -217,6 +221,7 @@ module.exports = {
   inputError: inputError,
   serviceError: serviceError,
   printSuccess: printSuccess,
+  printErrorWithHintAndExit: printErrorWithHintAndExit,
   printErrorAndExit: printErrorAndExit,
   printDevice: printDevice,
   createDeviceJSONObject: createDeviceJSONObject,

error-hints.js

@@ -0,0 +1,5 @@
+"use strict";
+
+module.exports = {
+    amqpLinkStolen: 'This issue can occur if you have two services listening in the same consumer group. Specify a different consumer group with the `-c` flag.\nEx. `iothub-explorer monitor-events --login "<connstr>" -c testGroup`\nMore info on consumer groups: https://aka.ms/Mf8kgi'
+};

iothub-explorer-monitor-events.js

@@ -14,6 +14,8 @@ var Promise = require('bluebird');
 // local dependencies
 var inputError = require('./common.js').inputError;
 var serviceError = require('./common.js').serviceError;
+var printErrorWithHintAndExit = require('./common.js').printErrorWithHintAndExit;
+var errorHints = require('./error-hints.js');
 
 // Azure Event Hubs dependencies
 var EventHubsClient = require('azure-event-hubs').Client;
@@ -73,6 +75,9 @@ var monitorEvents = function () {
               return ehClient.createReceiver(consumerGroup, partitionId, { 'startAfterTime': startTime })
                 .then(function (receiver) {
                   receiver.on('errorReceived', function (error) {
+                    if (error.transport && error.transport.condition.indexOf('amqp:link:stolen') >= 0) {
+                      printErrorWithHintAndExit(error.message, errorHints.amqpLinkStolen);
+                    }
                     serviceError(error.message);
                   });
                   receiver.on('message', function (eventData) {