in reply to Little annoying mistakes ... of others
I am sure I could come up with a laundry list but my mind is on other things (family isn't feeling well). The one that bugs me is not considering defined values that evaluate to false when setting up a conditional. Since I am guilty of this, let me give an example:
my $file = $ARGV or die "Usage: $0 <input_file>";
open(my $fh, '<', $file) or die "Unable to open '$file' for reading: $
While I think it is uncommon that someone would name their file '0', it is possible. In other examples, the oversight might be the empty string ''. As a reference, see True and False (aka Booleans). I know that 5.10 introduced the // operator which is great.