add support for ESM

[haroun]

Summary

Add ESM support

What are the specific steps to test this change?

1. npm test
2. you can use starter kit essentials ESM branch https://github.com/apostrophecms/starter-kit-essentials/tree/esm
3. you can use starter kit assembly essentials ESM branch https://github.com/apostrophecms/starter-kit-assembly-essentials/tree/esm

What kind of change does this PR introduce?

(Check at least one)

• Bug fix
• New feature
• Refactor
• Documentation
• Build-related changes
• Other

Make sure the PR fulfills these requirements:

• It includes a) the existing issue ID being resolved, b) a convincing reason for adding this feature, or c) a clear description of the bug it resolves
• The changelog is updated
• Related documentation has been updated
• Related tests have been updated

If adding a new feature without an already open issue, it's best to open a feature request issue first and wait for approval before working on it.

Other information:

[boutell]

Excited that you're working on this. Some comments re: uniqueness issues that might or might not still be a real thing.

[boutell]

Excited that you're working on this. Some comments re: uniqueness issues that might or might not still be a real thing.

[boutell]

Excited that you're working on this. Some comments re: uniqueness issues that might or might not still be a real thing.

[boutell]

Good stuff, minor notes

[boutell]

I'm trying out ESM, and I tried the incremental path of renaming app.js to app.mjs and making it an ES module, and leaving everything else alone to start. That seems to work fine. The page manager comes up OK, for instance.

Then I tried changing modules/default-page/index.js to index.mjs and exporting its contents the ESM way. This fails, the page manager does not show anything and I get browser console errors. If I click New Page, I get a server console error.

Is this kind of incremental transition approach supported? It seems it would be hard to transition otherwise as people will have a mix of module versions etc.

My code is in incremental-esm in testbed. I start it manually with node app.mjs as I haven't touched package.json.

@apostrophecms/page: api-error: manager.newInstance is not a function
 {
  module: '@apostrophecms/page',
  type: 'api-error',
  severity: 'error',
  url: '/api/v1/@apostrophecms/page?aposMode=draft&aposLocale=en',
  path: '/api/v1/@apostrophecms/page',
  method: 'POST',
  ip: '::1',
  query: { aposMode: 'draft', aposLocale: 'en' },
  requestId: 'n3truoelseeqybl6xgwoun9t',
  name: 'error',
  status: 500,
  stack: [
    'at Object.newChild (/Users/boutell/apostrophecms/apostrophe/modules/@apostrophecms/page/index.js:1411:30)',
    'at post (/Users/boutell/apostrophecms/apostrophe/modules/@apostrophecms/page/index.js:465:21)',
    'at process.processTicksAndRejections (node:internal/process/task_queues:95:5)',
    'at async /Users/boutell/apostrophecms/apostrophe/modules/@apostrophecms/module/index.js:191:30'
  ],
  errorPath: undefined,
  data: {}
}

[boutell]

My bug is not a bug. We will document that you can't mix .js and .mjs, you must go all the way to "type": "module" and update your .js to ESM syntax.