This FIXME belongs to a code example that was imported from the
internet. As we aren't going to do anything about it, I prefer to remove
it so it stops from appearing on searches.
ActionCable was throwing a "Existing connection must be closed before
opening" exception which was being picked up as a production issue in
our error monitoring software. Since this happens pretty often on any
device that allows the browser to sleep (mobile) this error was getting
triggered often.
This change removes the exception, but keeps logging the occurrence. We
now return `false` to let the caller now that `open` failed.
