Feedback loop

Author: arcanis

doc/api/packages.md

@@ -1022,8 +1022,8 @@ Each package entry has the following fields:
 When a bare specifier is encountered:
 
 1. Node.js determines which package performs the resolution request.
-    * If possible the package ID for the importer file should be provided to the resolution algorithm.
-    * Failing that, the resolution will check if the file path is within any package's `path`.
+   * If possible the package ID for the importer file should be provided to the resolution algorithm.
+   * Failing that, the resolution will check if the file path is within any package's `path`.
 2. If no package ID is provided and the importing file is not within any mapped package, an
    [`ERR_PACKAGE_MAP_EXTERNAL_FILE`][] error is thrown.
 3. Node.js looks up the specifier's package name in the importing package's

lib/internal/modules/esm/resolve.js

@@ -28,7 +28,7 @@ const { BuiltinModule } = require('internal/bootstrap/realm');
 const { realpathSync } = require('fs');
 const { getOptionValue } = require('internal/options');
 // Do not eagerly grab .manifest, it may be in TDZ
-const { sep, posix: { relative: relativePosixPath }, resolve } = require('path');
+const { sep, posix: { relative: relativePosixPath }, resolve, join } = require('path');
 const { URL, pathToFileURL, fileURLToPath, isURL, URLParse } = require('internal/url');
 const { getCWDURL, setOwnProperty } = require('internal/util');
 const { canParse: URLCanParse } = internalBinding('url');
@@ -771,7 +771,7 @@ function packageResolve(specifier, base, conditions) {
       throw new ERR_MODULE_NOT_FOUND(specifier, fileURLToPath(base), null);
     }
     const { packagePath, subpath } = mapped;
-    packageJSONPath = packagePath + '/package.json';
+    packageJSONPath = join(packagePath, 'package.json');
     packageJSONUrl = pathToFileURL(packageJSONPath);
     packageSubpath = subpath;
   } else {

lib/internal/modules/package_map.js

@@ -10,7 +10,7 @@ const {
 } = primordials;
 
 const assert = require('internal/assert');
-const { getLazy } = require('internal/util');
+const { emitExperimentalWarning, getLazy } = require('internal/util');
 const { resolve: pathResolve, dirname } = require('path');
 const { fileURLToPath } = require('internal/url');
 
@@ -30,7 +30,6 @@ const PROTOCOL_REGEXP = /^[a-zA-Z][a-zA-Z0-9+\-.]*:\/\//;
 // Singleton - initialized once on first call
 let packageMap;
 let packageMapPath;
-let emittedWarning = false;
 
 /**
  * @typedef {object} PackageMapEntry
@@ -208,7 +207,7 @@ function parsePackageName(specifier) {
 function loadPackageMap(configPath) {
   let content;
   try {
-    content = fs.readFileSync(configPath, 'utf8');
+    content = fs.readFileSync(configPath);
   } catch (err) {
     if (err.code === 'ENOENT') {
       throw new ERR_PACKAGE_MAP_INVALID(configPath, 'file not found');
@@ -226,19 +225,6 @@ function loadPackageMap(configPath) {
   return new PackageMap(configPath, data);
 }
 
-/**
- * Emit experimental warning on first use.
- */
-function emitExperimentalWarning() {
-  if (!emittedWarning) {
-    emittedWarning = true;
-    process.emitWarning(
-      'Package map resolution is an experimental feature and might change at any time',
-      'ExperimentalWarning',
-    );
-  }
-}
-
 /**
  * Get the singleton package map, initializing on first call.
  * @returns {PackageMap|null}
@@ -252,8 +238,15 @@ function getPackageMap() {
     return null;
   }
 
-  emitExperimentalWarning();
-  packageMap = loadPackageMap(pathResolve(packageMapPath));
+  emitExperimentalWarning('Package maps');
+
+  try {
+    packageMap = loadPackageMap(pathResolve(packageMapPath));
+  } catch (err) {
+    packageMap = new PackageMap(packageMapPath, { packages: {} });
+    throw err;
+  }
+
   return packageMap;
 }
 
@@ -262,7 +255,7 @@ function getPackageMap() {
  * @returns {boolean}
  */
 function hasPackageMap() {
-  return getPackageMap() !== null;
+  return !!getPackageMapPath();
 }
 
 /**