module: runtime deprecate invalid package.json main entries

PR-URL: https://github.com/nodejs/node/pull/37204
Fixes: https://github.com/nodejs/node/issues/26588
Reviewed-By: Guy Bedford <guybedford@gmail.com>
Reviewed-By: Geoffrey Booth <webmaster@geoffreybooth.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

doc/api/deprecations.md

@@ -2350,12 +2350,15 @@ with no performance impact since Node.js 10.
 ### DEP0128: modules with an invalid `main` entry and an `index.js` file
 <!-- YAML
 changes:
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/37204
+    description: Runtime deprecation.
   - version: v12.0.0
     pr-url: https://github.com/nodejs/node/pull/26823
     description: Documentation-only.
 -->
 
-Type: Documentation-only (supports [`--pending-deprecation`][])
+Type: Runtime
 
 Modules that have an invalid `main` entry (e.g., `./does-not-exist.js`) and
 also have an `index.js` file in the top level directory will resolve the

lib/internal/modules/cjs/loader.js

@@ -352,7 +352,7 @@ function tryPackage(requestPath, exts, isMain, originalPath) {
       err.requestPath = originalPath;
       // TODO(BridgeAR): Add the requireStack as well.
       throw err;
-    } else if (pendingDeprecation) {
+    } else {
       const jsonPath = path.resolve(requestPath, 'package.json');
       process.emitWarning(
         `Invalid 'main' field in '${jsonPath}' of '${pkg}'. ` +

test/parallel/test-module-loading-deprecated.js

@@ -1,5 +1,3 @@
-// Flags: --pending-deprecation
-
 'use strict';
 
 const common = require('../common');

test/sequential/test-module-loading.js

@@ -29,8 +29,7 @@ const path = require('path');
 
 const backslash = /\\/g;
 
-if (!process.env.NODE_PENDING_DEPRECATION)
-  process.on('warning', common.mustNotCall());
+process.on('warning', common.mustCall());
 
 console.error('load test-module-loading.js');
 
@@ -107,7 +106,16 @@ const d2 = require('../fixtures/b/d');
 assert.strictEqual(require('../fixtures/packages/index').ok, 'ok');
 assert.strictEqual(require('../fixtures/packages/main').ok, 'ok');
 assert.strictEqual(require('../fixtures/packages/main-index').ok, 'ok');
+
+common.expectWarning(
+  'DeprecationWarning',
+  "Invalid 'main' field in '" +
+  require.resolve('../fixtures/packages/missing-main/package.json') +
+  "' of 'doesnotexist.js'. Please either fix that or report it to the" +
+  ' module author',
+  'DEP0128');
 assert.strictEqual(require('../fixtures/packages/missing-main').ok, 'ok');
+
 assert.throws(
   () => require('../fixtures/packages/missing-main-no-index'),
   {