Cool, I refactored as:
```javascript
      Utils.safeWakeLock({timeoutMs: 30000}, function(done) {
        try {
          this[messageHandlerMapping[message.data.type]].call(
            this, message, done);
        } catch (err) {
          console.error('Error calling handler', err);
          done();
          throw err;
        }
      }.bind(this));
```

Much simpler/less indentation now!