Prevent errors in get_updates_success from stopping the event loop

Add try/catch blocks to get_updates_success and send a blueslip error on
errors we catch. This will let get_updates_success return successfully
so that the next call to get_updates will start immediately.

(imported from commit 44d8b85d9d8e930a5552a5fbf4af1d0e5e8c07e8)

static/js/tutorial.js

@@ -504,3 +504,6 @@ exports.initialize = function () {
 
 return exports;
 }());
+if (typeof module !== 'undefined') {
+    module.exports = tutorial;
+}