Provide a more user friendly message when an export is cancelled

AnaplanIdeas

Description of the enhancement:

Run an export from a model (helps if the export takes a few seconds).
Click Cancel when the browser asks you to save the file.
The export will fail and the message in Anaplan is:

{code:none}
An internal error occurred.
Client abort: java.io.IOException: Broken pipe(caused by: I o: Broken pipe)
{code}

It would help if this message was more user friendly.

AnaplanIdeas

Status changed to: In Review