Can't import 'child_process' JavaScript module to a Svelte app

I have a shell.mjs file with the following function shell():

import { exec } from 'child_process';

export function shell() {

  let command_test = 'echo hello';
  
  exec(`${command_test}`, (err, stdout, stderr) => {
    if (err) {
      //some err occurred
      console.error(err)
    } else {
    // the *entire* stdout and stderr (buffered)
    string = `${stdout}`;
    console.log(`stdout: ${stdout}`);
    console.log(`stderr: ${stderr}`);
    }
  });
}

When run on its own using node shell.mjs, the function works well.

However, when I try to import shell() to a Svelte app (created using this template: https://github.com/sveltejs/template), and run it in the browser using npm run dev (using Rollup), Rollup and the JavaScript console both tell me that they cannot find the 'child_process' module. Here's the error message from Rollup:

(!) Missing global variable name Use output.globals to specify browser global variable names corresponding to external modules child_process (guessing 'child_process')

And from JavaScript:

ReferenceError: Can't find variable: child_process

That's the code that I use in App.svelte to call the shell() function:

<script>
    import { shell } from './shell.mjs'
    shell();
</script>

App.svelte is then called in main.js:

import App from './App.svelte';

const app = new App({
    target: document.body
});

export default app;

How can I fix that?