Fix removing stmts with missing enz/subj
Fix removing stmts with missing enz/subj

sorgerlab/belpy,johnbachman/indra,pvtodorov/indra,bgyori/indra,sorgerlab/indra,sorgerlab/indra,johnbachman/belpy,pvtodorov/indra,sorgerlab/belpy,sorgerlab/belpy,pvtodorov/indra,sorgerlab/indra,bgyori/indra,bgyori/indra,pvtodorov/indra,johnbachman/belpy,johnbachman/belpy,johnbachman/indra,johnbachman/indra