RaP: Fix error message when shared notes could not be archived.

It used to print:

Failed to download file: undefined local variable or method `respose' for BigBlueButton:Module
Did you mean?  response

because the incorrect variable name was used in the error message.

There was no effect other than the message in the log, since the shared notes
couldn't be archived anyways, and the only thing the exception did was ...
prevent the shared notes from being archived.