wrapping remote data handling in try catch with error notification

Gracefully emit an event when generating the waveform produces an error. 
What error do you try to catch? The `WaveformData.create` or the resampling?

I strongly suggest to emit an `'error'` event, with an error object containing the reason of that error. It might be a ViewError, a WaveformData error or simply a standard error to start with.