Replace error with return synth
Replace error with return synth

`error` = Varnish 3 syntax
rweich/puppet-varnish,maxchk/puppet-varnish,interlegis/puppet-varnish,interlegis/puppet-varnish,bigon/puppet-varnish,sanoma-technology/puppet-varnish,joshuaspence/puppet-varnish,sanoma-technology/puppet-varnish,maxchk/puppet-varnish,rweich/puppet-varnish,bigon/puppet-varnish,voroniys/puppet-varnish,voroniys/puppet-varnish,joshuaspence/puppet-varnish