500 Internal server error when accessing some documents with edit app

[cziaarm]

OS and browser(s) [Windows 10] Chrome OS and browser(s) [Linux] Firefox

URL: https://transkribus.eu/readTest/view/2305/4949/1

Screen shots : https://drive.google.com/open?id=0B7dmP0OCT3cnRmNFNkpmYV9xUzA

Steps to reproduce: Follow Url provided

Expected results and actual results : Expected: edit/view for a document. Actual : "Server Error (500)" message

Any other information: The Document IMAGES (4949) loads OK using the expert client and has 4 pages. Error on dev shows edit/templates/edit/correct.html, error at line 458

[jnphilipp]

Caused by documents with out lines.