Ensure all exceptions are objects 

local $SIG{__DIE__} = sub {
    my $error = shift;
    if(UNIVERSAL::isa($error, 'Exception::Class')) {
        die $error; # re-throw
    }
    else {
        die MyException::Default->throw(
            message => "$error"
        );
    }
};

• Otherwise don’t use $SIG{__DIE__} – it’s global
• See also: $^S or $EXCEPTIONS_BEING_CAUGHT