update the if check for checkIfPoll function

Author: dhingrak

src/js/modules/projections/services/AtomEventsReader.js

@@ -40,6 +40,10 @@ define(['./_module'], function (app) {
 			}
 
 			function checkIfPoll (previous, headOfStream, onContinuePollCallback, doNotPollCallback) {
+
+				if (typeof result.previous.uri === "undefined") {
+					return;
+				}
 				if(!headOfStream){
 					doNotPollCallback();
 					return;