You are trying to remove undefined elements in a list?

my @list = ('foo', 'bar', undef, 'batz');
my @clean_list;
for (@list) {if (defined) { push (@clean_list, $_); } }
@list = @clean_list;
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Change the first and last lines to point to your object's list and you're all set. There may be better ways to do this, but this works.

Update:ichimunki notes the grep examples and wishes he'd thought of that. :)