module: throw an error for invalid package.json main entries

We currently ignore invalid `main` entries in package.json files.
This does not seem to be very user friendly as it's certainly an
error if the `main` entry is not a valid file name. So instead of
trying to resolve the file otherwise, throw an error immediately to
improve the user experience.
To keep it backwards compatible `index.js` files in the same directory
as the `package.json` will continue to be resolved instead but that
behavior is now deprecated.

PR-URL: https://github.com/nodejs/node/pull/26823
Fixes: https://github.com/nodejs/node/issues/26588
Reviewed-By: Guy Bedford <guybedford@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/test/parallel/test-module-loading-deprecated.js b/test/parallel/test-module-loading-deprecated.js
new file mode 100644
index 0000000000..3aa81eea6e
--- /dev/null
+++ b/test/parallel/test-module-loading-deprecated.js
@@ -0,0 +1,12 @@
+// Flags: --pending-deprecation
+
+'use strict';
+
+const common = require('../common');
+const assert = require('assert');
+
+common.expectWarning('DeprecationWarning', {
+  DEP0128: /^Invalid 'main' field in '.+main[/\\]package\.json' of 'doesnotexist\.js'\..+module author/
+});
+
+assert.strictEqual(require('../fixtures/packages/missing-main').ok, 'ok');