frontend_example with PyInstaller

Hello.

I'm just asking since I'm curious about one aspect of the project. While trying to make a standalone binary from the [frontend_example.py](https://github.com/google/openhtf/blob/master/examples/frontend_example.py), it launches but I end up with a "500: Internal Server Error" message in the browser. This is it, no error in terminal. I assume that the binary isn't bundling the correct resources or that the path is different than when running from local script like in SO thread [Bundling data files with PyInstaller (--onefile)](https://stackoverflow.com/a/44352931).

If the above assumption would be correct, most likely I'd have to figure out a way to swizzle the path to [openhtf/openhtf/output/web_gui/dist/](https://github.com/google/openhtf/tree/master/openhtf/output/web_gui/dist) folder so that the server serves these contents or something else would be necessary?

Best regards,