Thanks for making a pull request to converse.js!

Before submitting your request, please make sure the following conditions are met:

- [ ] Add a changelog entry for your change in `CHANGES.md`
- [ ] When adding a configuration variable, please make sure to
      document it in `docs/source/configuration.rst`
- [ ] Please add a test for your change. Tests can be run in the commandline
      with `make check` or you can run them in the browser by running `make serve`
      and then opening `http://localhost:8000/tests.html`.