give some debug message regarding why export might fail
switch the notification to be a prompt and allow for the user to go to the edit unit page which contains the module in error. Otherwise, present the raw exception message and allow user to go to the course outline page.
handle exceptions inside the outer exception handling
implement PR feedback
get_item -> get_instance
Studio: revises export prompt control copy
Merge pull request #589 from edx/fix/cdodge/better-export-error-messaging

give some debug message regarding why export has failed