$ perl -le " use strict; use diagnostics; my $peter; print scalar @$peter;
Can't use an undefined value as an ARRAY reference at -e line 1 (#1)
    (F) A value used as either a hard reference or a symbolic reference must
    be a defined value.  This helps to delurk some insidious errors.

Uncaught exception from user code:
        Can't use an undefined value as an ARRAY reference at -e line 1.