my %runmodes = (
	config_item => 'regular',
	action1 => sub{ print "action = 1" },
	action2 => sub{ print "action = 2" },
	action3 => {
		config_item => 'special',
		subroutine => sub{ print "action = 3" },
	},
);

sub get_config_item {
	my( $runmodes, $action ) = @_;

	my $config_item = $runmodes->{ config_item };

	if( exists $runmodes->{ $action }{ subroutine } ) { # error line
		&{ $runmodes->{ $action }{ subroutine }};
		$config_item = $runmodes->{ $action }{ config_item };
	}
	else {
		&{ $runmodes->{ $action }}
	}

	return $config_item;
}

print ", ", get_config_item( \%runmodes, "action3" ), "\n";
print ", ", get_config_item( \%runmodes, "action1" ), "\n";


# OUTPUT
#
# action = 3, special
# Not a HASH reference at str.pl line 22.

##</code><code>##

my %runmodes = (
	config_item => 'regular',
	action1 => { subroutine => sub{ print "action = 1" }},
	action2 => { subroutine => sub{ print "action = 2" }},
	action3 => {
		config_item => 'special',
		subroutine => sub{ print "action = 3" }},
	},
);