Feedback

Author: arcanis

lib/internal/modules/cjs/loader.js

@@ -662,6 +662,8 @@ function trySelf(parentPath, request, conditions) {
 function tryPackageMapResolveCJS(request, parent, conditions) {
   if (!hasPackageMap()) { return undefined; }
 
+  // If the resolution has no parent, use the current working directory. This
+  // usually happens when running `node -e 'require("some-package")'`.
   const parentPath = parent?.filename ?? process.cwd() + path.sep;
   const mapped = packageMapResolve(request, parentPath);
 

lib/internal/modules/package_map.js

@@ -10,7 +10,7 @@ const {
 } = primordials;
 
 const assert = require('internal/assert');
-const { emitExperimentalWarning, getLazy } = require('internal/util');
+const { emitExperimentalWarning, getLazy, setOwnProperty } = require('internal/util');
 const { resolve: pathResolve, dirname } = require('path');
 const { fileURLToPath } = require('internal/url');
 
@@ -211,10 +211,9 @@ function loadPackageMap(configPath) {
   try {
     content = fs.readFileSync(configPath);
   } catch (err) {
-    if (err.code === 'ENOENT') {
-      throw new ERR_PACKAGE_MAP_INVALID(configPath, 'file not found');
-    }
-    throw new ERR_PACKAGE_MAP_INVALID(configPath, err.message);
+    const error = new ERR_PACKAGE_MAP_INVALID(configPath, 'failed to read');
+    setOwnProperty(error, 'cause', err);
+    throw error;
   }
 
   // Resolve symlinks so that stored paths match the realpath'd module paths
@@ -225,7 +224,9 @@ function loadPackageMap(configPath) {
   try {
     data = JSONParse(content);
   } catch (err) {
-    throw new ERR_PACKAGE_MAP_INVALID(configPath, `invalid JSON: ${err.message}`);
+    const error = new ERR_PACKAGE_MAP_INVALID(configPath, `invalid JSON`);
+    setOwnProperty(error, 'cause', err);
+    throw error;
   }
 
   return new PackageMap(configPath, data);
@@ -249,6 +250,9 @@ function getPackageMap() {
   try {
     packageMap = loadPackageMap(pathResolve(packageMapPath));
   } catch (err) {
+    // Fallback to an empty package map to avoid repeatedly trying
+    // to load the broken package map file. Subsequent resolutions
+    // will still fail to resolve due to the package map being empty.
     packageMap = new PackageMap(packageMapPath, { packages: {} });
     throw err;
   }

test/es-module/test-esm-package-map.mjs

@@ -160,7 +160,7 @@ describe('ESM: --experimental-package-map', () => {
       ], { cwd: fixtures.path('package-map/root') });
 
       assert.match(stderr, /ERR_PACKAGE_MAP_INVALID/);
-      assert.match(stderr, /not found/);
+      assert.match(stderr, /no such file or directory/);
       assert.notStrictEqual(code, 0, stderr);
     });