Kakoune: nix.kak parse a certain nested string expression incorrectly

[omasanori]

Steps

Open test.nix with the content below:

f = x: ''
  ${g ({y}: ''
  '') 0}
'';

(the real world example: https://github.com/NixOS/nixpkgs/blob/a5f5d020c69c22ddc6be48123ef4d30fd262c403/pkgs/development/compilers/graalvm/default.nix#L11-L86)

Outcome

The nested string is highlighted incorrectly.

Expected

The text from '' in line 1 to '' in line 4 is recognized as a single string.

[eraserhd]

I think this is the same issue as #1670.