Fixed an exception, happens when ZenDesk floating widget is not loaded (#3687)
Fixed an exception, happens when ZenDesk floating widget is not loaded (#3687)

* Fixed ZenDesk widget exception when floating button is not loaded

* Added a comment

* dont run code of iframe is null

mitodl/micromasters,mitodl/micromasters,mitodl/micromasters,mitodl/micromasters