Plugin conflict: [vite:css] plugins[i] is not a function

[theprojectsomething]

Describe the bug

I'm attempting to allow import assertions in a vite build using the acorn plugin acorn-import-assertions e.g:

// vite.config.js
import { defineConfig } from 'vite'
import { importAssertions } from 'acorn-import-assertions';

export default defineConfig({
  build: {
    rollupOptions: {
      // note the plugin isn't instantiated here
      acornInjectPlugins: [ importAssertions ],
    },
  },
})

// entry.js
import data from 'data.json' assert { type: 'json' }

On build vite throws an error: [vite:css] plugins[i] is not a function that tracks back to a function (Parser.extend) in one of the node chunks in the dist folder. If I patch that file (to check for a function type before attempting to execute it) everything works as expected.

Assuming this is a conflict with PostCSS or similar due to the extra baggage on the end of the import syntax, but not sure where to begin looking as I couldn't find any reference in source.

Any help much appreciated!

Reproduction

Minimal reproduction => npm run dev

System Info

System:
    OS: macOS 12.4
    CPU: (8) x64 Intel(R) Core(TM) i7-6700HQ CPU @ 2.60GHz
    Memory: 1.15 GB / 16.00 GB
    Shell: 3.2.57 - /bin/bash
  Binaries:
    Node: 15.2.0 - ~/.nvm/versions/node/v15.2.0/bin/node
    Yarn: 1.22.10 - /usr/local/bin/yarn
    npm: 7.0.8 - ~/.nvm/versions/node/v15.2.0/bin/npm
  Browsers:
    Chrome: 101.0.4951.64
    Edge: 101.0.1210.53
    Firefox Developer Edition: 101.0
    Safari: 15.5
  npmPackages:
    vite: ^2.9.9 => 2.9.9

Used Package Manager

npm

Logs

No response

Validations

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• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Make sure this is a Vite issue and not a framework-specific issue. For example, if it's a Vue SFC related bug, it should likely be reported to https://github.com/vuejs/core instead.
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• The provided reproduction is a minimal reproducible example of the bug.

[sapphi-red]

For a workaround, change it to non array like this.

acornInjectPlugins: importAssertions,