Error on Testat submission

The Testat Checker fails on the second Testat Submission of Dbs1 u13-Team06 / 2020 with following Error:

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==================================== ERRORS ====================================
___________ ERROR at setup of test_submission2_contains_needed_files ___________
E   ValueError: Unexpected value for 'items', must be a non empty list, got <class 'list'>
---------------------------- Captured stdout setup -----------------------------
cols[0]={ResTarget}
cols[1]={ResTarget}
cols[2]={ResTarget}
cols[0]={ResTarget}
cols[1]={ResTarget}
cols[0]={ResTarget}
cols[1]={ResTarget}
cols[2]={ResTarget}
cols[3]={ResTarget}
cols[0]={ResTarget}
cols[1]={ResTarget}
cols[2]={ResTarget}
cols[3]={ResTarget}
cols[4]={ResTarget}
cols[0]={ResTarget}
cols[1]={ResTarget}
cols[2]={ResTarget}
cols[0]={ResTarget}
cols[1]={ResTarget}
cols[2]={ResTarget}
cols[0]={ResTarget}
cols[1]={ResTarget}
cols[2]={ResTarget}
________________ ERROR at setup of test_submission_contains_pdf ________________
E   ValueError: Unexpected value for 'items', must be a non empty list, got <class 'list'>
________ ERROR at setup of test_submission_contains_only_allowed_files _________
E   ValueError: Unexpected value for 'items', must be a non empty list, got <class 'list'>
_______________ ERROR at setup of test_identifier_are_snake_case _______________
E   ValueError: Unexpected value for 'items', must be a non empty list, got <class 'list'>
____________________ ERROR at setup of test_correct_syntax _____________________
E   ValueError: Unexpected value for 'items', must be a non empty list, got <class 'list'>
________________ ERROR at setup of test_no_query_with_inherits _________________
E   ValueError: Unexpected value for 'items', must be a non empty list, got <class 'list'>
17 deselected, 6 errors in 0.10s