Wavetable Synth demo breaks after switching from polyphonic mode

[terryzfeng]

Steps to reproduce:

1. Open Demo: https://googlechromelabs.github.io/web-audio-samples/demos/wavetable-synth/
2. Open console
3. Type context.resume()
4. Check box to switch to polyphonic mode
5. Uncheck box to switch back to monophonic

Error message: Uncaught DOMException: Failed to set the 'buffer' property on 'AudioBufferSourceNode': Cannot set buffer to non-null after it has been already been set to a non-null buffer

[mjwilson-google]

I can't reproduce this. Are you launching with the no user gesture command line flag?

[Kizjkre]

I was able to reproduce this through a more convoluted method, updated in the issue description.

[mjwilson-google]

I reproduced it with the updated steps, thank you!