Allow dimensions in MCreator's interface to have air as a valid underground block

In the dimension element, the underground block disallows air. However, when I edited the JSON file to forcefully use air, I got a working, empty dimension. If the biome at 0, 0 is The Void, the stone platform from the void superflat preset also generates.

What is the reason behind limiting air? Can the limit be removed? I'd love it if we don't have to lock the entire element for a single-line change in order to have an empty dimension