Cannot read property 'length' of undefined
When starting Homebridge, everything runs fine. The app shows the computer as off, but when I try to power on, I see homebridge stop and provide the following:

 Call get for undefined, return true
/usr/local/lib/node_modules/homebridge-wol/node_modules/wake_on_lan/wake_on_lan.js:12
  if (mac.length == 2 * mac_bytes + (mac_bytes - 1)) {
         ^

TypeError: Cannot read property 'length' of undefined
    at Object.exports.createMagicPacket (/usr/local/lib/node_modules/homebridge-wol/node_modules/wake_on_lan/wake_on_lan.js:12:10)
    at Object.exports.wake (/usr/local/lib/node_modules/homebridge-wol/node_modules/wake_on_lan/wake_on_lan.js:46:30)
    at wake (/usr/local/lib/node_modules/homebridge-wol/index.js:69:9)
    at Computer.<anonymous> (/usr/local/lib/node_modules/homebridge-wol/index.js:41:11)
