Skip externalAgentSupport call when pageChangeData does not contain a spineItem value.
MODIFY
js/views/reader_view.js
js/views/reader_view.js
@@ -280,6 +280,8 @@ var ReaderView = function (options) {
_.defer(function () {
Globals.logEvent("PAGINATION_CHANGED", "EMIT", "reader_view.js");
self.emit(Globals.Events.PAGINATION_CHANGED, pageChangeData);
+
+ if (!pageChangeData.spineItem) return;
_.defer(function () {
_externalAgentSupport.updateContentDocument(pageChangeData.spineItem);
});

Skip externalAgentSupport call when pageChangeData does not contain a spineItem value.