esm: fix emit deprecation on legacy main resolve

[aduh95]

#48325 introduced a bug where the deprecation is thrown for every resolve. This PR fixes that.

Refs: #48325

[nodejs-github-bot]

Review requested:

• @nodejs/loaders
• @nodejs/modules

[ljharb]

probably should add a test case of an ESM "main" that omits the leading ./?

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/52626/

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/52629/

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/52633/

[H4ad]

I think this change can be simplified to:

/**
 * Legacy CommonJS main resolution:
 * 1. let M = pkg_url + (json main field)
 * 2. TRY(M, M.js, M.json, M.node)
 * 3. TRY(M/index.js, M/index.json, M/index.node)
 * 4. TRY(pkg_url/index.js, pkg_url/index.json, pkg_url/index.node)
 * 5. NOT_FOUND
 * @param {URL} packageJSONUrl
 * @param {PackageConfig} packageConfig
 * @param {string | URL | undefined} base
 * @returns {URL}
 */
function legacyMainResolve(packageJSONUrl, packageConfig, base) {
  const packageJsonUrlString = packageJSONUrl.href;

  if (typeof packageJsonUrlString !== 'string') {
    throw new ERR_INVALID_ARG_TYPE('packageJSONUrl', ['URL'], packageJSONUrl);
  }

  const baseStringified = isURL(base) ? base.href : base;

  const resolvedOption = FSLegacyMainResolve(packageJsonUrlString, packageConfig.main, baseStringified);

  const baseUrl = resolvedOption <= legacyMainResolveExtensionsIndexes.kResolvedByMainIndexNode ? `./${packageConfig.main}` : '';
  const resolvedUrl = new URL(baseUrl + legacyMainResolveExtensions[resolvedOption], packageJSONUrl);

+ if (resolvedOption !== legacyMainResolveExtensionsIndexes.kResolvedByMain)
  emitLegacyIndexDeprecation(resolvedUrl, packageJSONUrl, base, packageConfig.main);
  return resolvedUrl;
}

The deprecation should be emitted for every case except from kResolvedByMain, ref: anonrig@a2a8e31#diff-b4c24f634e3741e5ad9e8c29864a48f2bd284a9d66d8fed3d077ccee0c44087bL160-L163

[nodejs-github-bot]

Landed in ffb1929