Easiest way is to Deparse it:

    $ perl -MO=Deparse tp.pl 
    'division'->Illegal('zero'->by('at' / 'tmp' / 'quine' . 'line'->pl(1)));
    tp.pl syntax OK

So I believe this is what causes it (note that "at" and "tmp" and such are "barewords"):

    $ perl -e 'at / tmp'
    Illegal division by zero at -e line 1.