TypeError: appCache is undefined[Learn More] when serving 0.0.0.0

[xobs]

Bug Template

Describe the bug
pxt serve is the only reliable way to share C++ code changes with others without deploying to makecode.com. By default, pxt serve binds to localhost. It is possible to tell pxt to bind to "ANY" by setting hostname to 0.0.0.0, however this produces very strange behavior.

To Reproduce
Steps to reproduce the behavior:

1. Install a pxt project, such as https://github.com/xobs/pxt-chibitronics/tree/rainbow-tape
2. Run pxt serve --hostname 0.0.0.0
3. A browser window opens. Change the address to the non-local interface address
4. See error

Expected behavior
The server should work normally, as long as the "local token" is presented.

Screenshots
Add screenshots to help explain your problem. You can copy paste the screenshot in the github report. The .gif screen recording is very useful as well.