When I click the add ons icon, it says “Error: Attempt to postMessage on disconnected port” in the add ons console (nothing in the normal browser console).
In all the examples, <name> is the value of the name property in the manifest.
They should probably clarify that they mean the native messaging manifest (ping_pong.json), not the extension manifest (manifest.json).
As for check_config_win.py, it just crashes:
key = winreg.OpenKey(getattr(winreg, root), key_path)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
FileNotFoundError: [WinError 2] The system could not find the specified file
edit:
I changed the name of the registry key while Firefox was running.
It didn’t become aware of the change immediately, I had to reload the extension first.
Unfortunately I had also tried “ping_pong”, and just tried it again (rebooted firefox after changing the key, then re-added the temporary add on), and I’m still getting the same error message.
I hadn’t noticed that check_config_win python file before, but upon trying it I get the same error as you did.