Starting grunt server via: grunt serve and got following error

Loading "connect_proxy.js" tasks...ERROR
>> TypeError: Cannot read property 'prototype' of undefined

The issue seems already raised on grunt-connect-proxy module already and it has already fixed for the new version, if you still face the error above, please try following command to solve it:

rm -rf node_modules/grunt-connect-proxy
npm install eventemitter3@0.1.6
npm install grunt-connect-proxy

It is because of the dependency: eventemitter3 that from version 0.1.6, it has been solved already, please use latest one.