Mid-song crash

[crism]

The song leader had just finished up, and I noticed he disappeared from the screen. I attempted to join bucket 6 myself, and got a crash with instructions to file a bug and this message:

NotFoundError: Node.removeChild: The node to be removed is not a child of this node
update_active_users@https://echo.jefftk.com/demo.js:1185:50
start_singing/<@https://echo.jefftk.com/demo.js:1971:26
server_metadata_received@https://echo.jefftk.com/app.js:1146:10
server_response/<@https://echo.jefftk.com/app.js:1293:12

So, here I am, filing a bug. Thank you!