Demo page player hangs when playing SNDH and then MOD

[Kabuto]

or the other way round, and there seem to be more cases where the player hangs when playing multiple songs.

Test procedure:

• Browser: Firefox or Chrome, Windows 10
• Open the demo page: https://demozoo.github.io/cowbell/
• Select the SNDH song from the dropdown
• Hit Play --> audio plays
• Select the MOD song from the dropdown --> audio stops
• Hit Play --> the player hangs

[glennlunder]

Confirmed.