Add debugging for new socket error

[nwalters512]

We're now seeing a fun new variety of error relating to setting up sockets:

Unhandled rejection (promise:  Promise {
 <rejected> TypeError: Cannot destructure property `courseId` of 'undefined' or 'null'.
   at Socket.socket.on (/home/waf/queue/build/socket/server.js:233:46)
   at <anonymous> } , reason:  TypeError: Cannot destructure property `courseId` of 'undefined' or 'null'.
   at Socket.socket.on (/home/waf/queue/build/socket/server.js:233:46)
   at <anonymous> ).

This PR adds explicit logging for when that fails to hopefully help trace the problem back to its source.

[vercel]

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