Added some handling for when the user tries to do an export with a bogus output_id
Added some handling for when the user tries to do an export with a bogus output_id


Former-commit-id: 909c1154da8a472d96e55b7fbdcf4a61e9fa030c [formerly b4a7ebf8659b17fa0147a3cb657072e833fee87d]
Former-commit-id: eb262632cef675092bd124bce23685b60c861be5
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine