Generate process seems fail when css variables start with a number (--0, --1)

[apomili]

Hi guys,
I'm using postcss-variable-compress to compress css variables from a very verbose framework, and now I have a problem with the critical css output.

There is no error in the process, but simply the file is not written to disk.

I tried prefixing all css variables with a letter and it works fine.

I understand that formally it is correct to have variables starting with a number, otherwise I will open an issue to postcss-variables-compress