In Socket.jsm, line 298 uses destructured assignment from a regular
expression.
var [match, code] = response.match(/^HTTP\/1.\d (\d{3})/);
However, if this returns null (as I did when the response was
"</stream:stream>" due to an error, the assignment causes an error (it
doesn't just assign to the first variable match). I believe you need to
either put this in a try-catch block or avoid destructured assignment,
as nice as it would be to do it that way...
best wishes,
Brett