module: use undefined if no main

If the package.json file does not have a "main" entry, return undefined
rather than an empty string. This is to make more consistent behavior.
For example, when package.json is a directory, "main" is undefined
rather than an empty string.

PR-URL: https://github.com/nodejs/node/pull/18593
Reviewed-By: Bradley Farias <bradley.meck@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Vladimir de Turckheim <vlad2t@hotmail.com>
Reviewed-By: Yuta Hiroto <hello@about-hiroppy.com>
Reviewed-By: Benedikt Meurer <benedikt.meurer@gmail.com>
Reviewed-By: Ali Ijaz Sheikh <ofrobots@google.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/test/parallel/test-module-binding.js b/test/parallel/test-module-binding.js
index bea0c91f0c..a3ebaf9e72 100644
--- a/test/parallel/test-module-binding.js
+++ b/test/parallel/test-module-binding.js
@@ -6,8 +6,9 @@ const { readFileSync } = require('fs');
 const { strictEqual } = require('assert');
 
 strictEqual(internalModuleReadJSON('nosuchfile'), undefined);
-strictEqual(internalModuleReadJSON(fixtures.path('empty.txt')), '');
-strictEqual(internalModuleReadJSON(fixtures.path('empty-with-bom.txt')), '');
+strictEqual(internalModuleReadJSON(fixtures.path('empty.txt')), undefined);
+strictEqual(internalModuleReadJSON(fixtures.path('empty-with-bom.txt')),
+            undefined);
 {
   const filename = fixtures.path('require-bin/package.json');
   strictEqual(internalModuleReadJSON(filename), readFileSync(filename, 'utf8'));