Jasper

The typings for this assembly package don't appear to reflect all of the extra capabilities provided by the library, e.g. 

As [discussed on Slack](https://fbphq.slack.com/archives/CTJAZQU4A/p1605614171113500) it'd be useful if the assembly package offered utilities for creating generator components.

### What happened? An error handler cannot be added to the Readable stream until an ID has been received from Asterisk, leaving a window where errors that are proxied from...