Fix null dereference in project_import_status

Merged Matthias Käppler requested to merge 214998-fix-null-deref into master

What does this MR do?

Fixes a null reference problem in the /import status endpoint. It only occurs when trying to fetch import status without ever having imported anything.

Closes #214998 (closed)

Does this MR meet the acceptance criteria?

Conformity

Availability and Testing

Addes a regression test.