[Bug] A delay in the permission function causes the menu to break

[edwardexo]

Describe the bug
Currently, the permission system is client-side. However, some information which I want to use for permissions is kept server-side.

I created a simple server-side callback dolu_tool:isAuthorized which returns true or false. I'm trying to use this callback in the permission function, but the menu breaks when using it.

To Reproduce
Steps to reproduce the behavior:

1. Create a server-side callback:

lib.callback.register('dolu_tool:isAuthorized', function(source)
    return true
end)

2. Use the server-side callback in the permission system.

Config.perimission =  function(type)
    return lib.callback.await('dolu_tool:isAuthorized', false)
end

3. Try to open the mapping tool.
4. The opened mapping menu is bugged and there's an error in the F8 console: Uncaught (in promise) SyntaxError: Unexpected end of JSON input (@dolu_tool/web/build/index.html:1).

Expected behavior
The menu should open correctly and not be bugged.

Screenshots
Screenshot of the error and you can see the menu is bugged (no text in the boxes).

Additional context
Seems that if you don't return the permission instantly, it breaks. You can also do Wait(100) before returning true/false and the same problem will happen.

I sometimes get the same error & bug totally randomly as well, without any changes to the script - similarly to #14

It seems if something is not loaded quick enough, the F8 HTML error appears and the menu gets bugged.

[dolutattoo]

Latest commit should fix this. If someone is able to build nui from source code and test