Issue with hterm.js, in `959a176466ad6dbeced12b019e9fa5b4a08056d2`

[maifeeulasad]

In the latest pull (959a176466ad6dbeced12b019e9fa5b4a08056d2), it's not rendering anything:

properties of undefined (reading 'style')
    at hterm.ScrollPort.setBackgroundColor (hterm.js:9380:18)
    at hterm.Terminal.setBackgroundColor (hterm.js:10908:22)
    at background-color (hterm.js:10571:22)
    at lib.PreferenceManager.notifyChange_ (hterm.js:2120:28)
    at lib.PreferenceManager.notifyAll (hterm.js:2100:14)
    at hterm.Terminal.<anonymous> (hterm.js:10848:21)
hterm.ScrollPort.setBackgroundC

Here is a snap:

Maybe I can try to fix it.