500 Internal Server Error

Technical details:
Error: access to uninitialised variable - (array element 0)
***  in function "PROJ_OBJECT_get_summary_data"
***  line: {L5} = {L4}[0]
***  call: PROJ_OBJECT_get_summary_data ([ix_recmon_record])
***  call: X_MI_get_object_summary_data ([ix_recmon_record])
***  call: MI_run_search ("collection", "(with spec_responsible_department_th_h from : to :.~ and (n...", "1")