# Previous (manual OO) code:
sub error_mode {                                                                
    my ($s, $mode) = @_;                                                        
    if ($mode) {                                                                
        $s->_err('Invalid error_mode', $s->{error_mode})                        
            unless $mode =~ /^(carp|error|both)$/;                              
        $s->{error_mode} = $mode;                                               
    }                                                                           
                                                                                
    $s->{error_mode};                                                           
}
##</code><code>##

# Converted to Mouse:
enum 'ErrorMode' => qw<carp error both>;
has 'error_mode' => ( is => 'rw', isa => 'ErrorMode', default => 'error' );
##</code><code>##

Attribute (error_mode) does not pass the type constraint because: Validation failed for 'ErrorMode' with value  at /usr/local/lib/x86_64-linux-gnu/perl/5.26.1/Mouse/Util.pm line 395.
        Mouse::Util::throw_error(Mouse::Meta::Attribute=HASH(0x56165c0b5528), "Attribute (error_mode) does not pass the type constraint beca"..., "data", "", "depth", -1) called at ./t/05-errors.t line 16