User is not able to export cucumber tests

Description Exporting Cucumber feature files fails with a 500 Internal Server Error.

Pre-conditions (None)

How to reproduce

1. Hide or disable the Issue link field from the Test screen.
2. Go to a Cucumber Test issue. (The bug appears to happen when this Test is linked to other issues, like Requirements, that have been deleted or have permission restrictions).
3. From the Test issue page, use the Xray action to "Generate Cucumber Feature files."

Actual result/Attachments The export fails. The UI shows an "Error exporting cucumber feature file" message, and the network request returns a 500 Internal Server Error.

Expected result The feature file should be generated successfully. 

Workaround
Add the Linked issues field to the corresponding Field Configuration and then be sure the field is present/not hidden in the respective Test Edit screen.