Prevent or show a warning if you overwrite a channel.

[casret]

Because it's pretty easy to overwrite a channel name with a different subscription:

actioncable-vue/src/cable.js

Line 71 in 4378b80

this._channels.subscriptions[

we've gotten into situations where we either leak subscriptions and get multiple calls to received with the same data, or lost a connection to a channel when trying to share it between components. It would be good to either warn or raise an exception if you are about to re-use the channel name. I think an error is probably warranted here since it's not a situation that you can recover from since AFAICT there is no way to now get a reference to the channel that was overwritten. I'd be happy to write a patch, just wanted to check if I was missing some nuance.

[mclintprojects]

Sorry. I didn't see this suggestion but it's a fantastic idea. I'll add this to my backlog.