How can the generator code be written to only produce dirt at 1 block flat in all directions?

[WithinAmnesia]

I got the script working but its buggy and has issues. the current world generator code looks okay in game but generated ~3 blocks high grass and it has trouble generating after a while and it makes bugs in the debugger window for the editor lol. How should be properly done so there are no bugs and it runs smooth and infinitely generates smooth running 1 block thick dirt chunks in compatibly mode?

Here is the gist of the 'generator_test.gd': https://gist.github.com/WithinAmnesia/025f8d1ae7b674fc2c2d4381e9e45c8b

I had to just turn off a lot of the BlockyGame generator like the trees but I used lots of # but I did not know what oi was doing 100% so I flew at it to get a working prototype good enough for rough testing which I did but it has bugs and runs not great play I feel there is a like one or two lines / parts of code that could generate 1 thick block of dirt in all x and z axis and have all the 2-16 above blocks be air filled. I think the air fill already works its just how to generate 1 block this of dirt is all on the 0 y / lowest block of the 1 chunk thick later. So its flat and using 1 thick blocks for infinite worlds. What are your thoughts and suggestions? What should be done here too? All feedback is welcome.
From: #101 (comment)

[WithinAmnesia]

I got the 1 thick block chunk generator to work but the multiplayer does not work for some reason or if it does only client 1 (host) and client 4 work as they join the world. I stuck with 3 layers of dirt and said good enough. It might be handy for water and things later. I'm not sure why the multiplayer did not work but hey I can live with a 3 block high flat chunk generator.