Remove any entries that only consist of NA from data.frames icc (Incompatible Component Causes) and outc (outcome definition) from an
epicmodel_steplist.
Value
An epicmodel_steplist object without entries in data.frame icc, which contain 'NA' in either id1 or id2 as well as entries in
data.frame outc that contain 'NA' in id_outc. If you made any changes, you need to call check_steplist() again.
