Steps to reproduce

1.  Go to: https://demo.magnolia-cms.com/.magnolia/admincentral#app:pages-app:detail;/sportstation/about:edit
2. Create a Variant for the Jumbotron but don't change anything
3. Go to the Translation Content Support App and try to export the page as Excel
4. Excel Export crashes 

.. Logs, screenshots, gifs...

Expected results

• Do the export properly and fail safe

.. Justify non-trivial expectations with a link to a doc or a relevant discussion.

Actual results

• See above

Workaround

• No

Development notes

Fix is easy. The Class requires a modification date at the line 76, The method .getTime() will fail if the mod date is null.

https://git.magnolia-cms.com/projects/ENTERPRISE/repos/content-translation-support/browse/magnolia-content-translation/src/main/java/info/magnolia/translation/io/writer/AbstractTranslationItemWriter.java#76