Submit the following patch to the maintainer of Error.pm: 
-exists $self->{'-value'} ? $self->{'-value'} : undef;
+exists $self->{'-value'} ? $self->{'-value'} : 0;

[download]
The bug is that 0+ should always return something that is a number. Undef, as you've discovered, isn't a number.
My criteria for good software:
  1. Does it work?
  2. Can someone else come in, make a change, and be reasonably certain no bugs were introduced?

In reply to Re: When numeric conversion overloading goes awry. by dragonchild
in thread When numeric conversion overloading goes awry. by dmitri

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