Xporter is not loading error's message

Xporter is not loading an error message in order to give user feedback.

Steps to reproduce the error

1. Update the maximum number of simultaneous requests to one
2. Make multiple single exports simultaneously
3. The user will get only a flag with "Error" without any message

Expected outcome

Users must have a message saying the simultaneous requests are above the limit as we already have for Bulk Export.

Actual outcome

Nothing is shown.