Make sure parameter is not null either.

Sometimes "links" parameter is null.

Supporting error message:
```
alert: [steward] exception diagnostic=Cannot read property 'length' of null
alert: [steward] exception stack=[{"fileName":"/home/pi/steward/steward/devices/devices-gateway/gateway-insteon-automategreen.js","lineNumber":103,"functionName":null,"typeName":null,"methodName":null,"columnNumber":28,"native":false},{"fileName":"/home/pi/steward/steward/node_modules/home-controller/node_modules/q/q.js","lineNumber":1887,"functionName":null,"typeName":null,"methodName":null,"columnNumber":17,"native":false},{"fileName":"/home/pi/steward/steward/node_modules/home-controller/node_modules/q/q.js","lineNumber":108,"functionName":"flush","typeName":"Object","methodName":null,"columnNumber":17,"native":false},{"fileName":"node.js","lineNumber":419,"functionName":"process._tickCallback","typeName":"process","methodName":"_tickCallback","columnNumber":13,"native":false}]
uncaught exception: TypeError: Cannot read property 'length' of null
```