Invalid className when issued from file with bracketed name

[ksesong]

Describe the bug

When setting styles on a .css.ts file that includes brackets in its name like [test].css.ts, the resulting styles from the output stylesheet have an invalid className, with a missing dot, such that the styles cannot be applied.

Link to reproduction

This sandbox reproduces the issue. Both divs should be yellow, but the file whose name uses brackets gets processed incorrectly.

System Info

Output of npx envinfo --system --npmPackages @vanilla-extract/css,@vanilla-extract/webpack-plugin,@vanilla-extract/esbuild-plugin,@vanilla-extract/vite-plugin,@vanilla-extract/sprinkles,webpack,esbuild,vite --binaries --browsers:

  System:
    OS: Linux 5.4 Debian GNU/Linux 10 (buster) 10 (buster)
    CPU: (12) x64 Intel(R) Core(TM) i7-8700 CPU @ 3.20GHz
    Memory: 3.27 GB / 62.73 GB
    Container: Yes
    Shell: 5.0.3 - /bin/bash
  Binaries:
    Node: 14.17.6 - ~/.nvm/versions/node/v14.17.6/bin/node
    Yarn: 1.22.11 - ~/.nvm/versions/node/v14.17.6/bin/yarn
    npm: 6.14.15 - ~/.nvm/versions/node/v14.17.6/bin/npm
  npmPackages:
    @vanilla-extract/css: 1.6.1 => 1.6.1
    @vanilla-extract/sprinkles: ^1.3.0 => 1.3.0
    @vanilla-extract/webpack-plugin: ^2.1.0 => 2.1.0
    webpack: ^5.36.1 => 5.58.1