Improve error message on missing worker
Improve error message on missing worker

ringo/ringojs,ashwinrayaprolu1984/ringojs,ringo/ringojs,Transcordia/ringojs,ashwinrayaprolu1984/ringojs,Transcordia/ringojs,oberhamsi/ringojs,ringo/ringojs,ashwinrayaprolu1984/ringojs,oberhamsi/ringojs,oberhamsi/ringojs,Transcordia/ringojs,Transcordia/ringojs,ringo/ringojs,ashwinrayaprolu1984/ringojs