fix: don't crash when can't resolve an env variable

ref pnpm/pnpm#5093

index.js

@@ -8,6 +8,7 @@ module.exports = (opts, types, defaults) => {
 	const conf = new Conf(Object.assign({}, _defaults.defaults, defaults), types);
 
 	conf.add(Object.assign({}, opts), 'cli');
+	const warnings = [];
 
 	if (require.resolve.paths) {
 		const paths = require.resolve.paths('npm');
@@ -25,7 +26,7 @@ module.exports = (opts, types, defaults) => {
 			 *  According to https://github.com/npm/cli/blob/86f5bdb91f7a5971953a5171d32d6eeda6a2e972/lib/npm.js#L258
 			 *  and https://github.com/npm/cli/blob/86f5bdb91f7a5971953a5171d32d6eeda6a2e972/lib/config/core.js#L92
 			 */
-			conf.addFile(path.resolve(path.dirname(npmPath), '..', 'npmrc'), 'builtin');
+			warnings.push(conf.addFile(path.resolve(path.dirname(npmPath), '..', 'npmrc'), 'builtin'));
 		}
 	}
 
@@ -36,7 +37,7 @@ module.exports = (opts, types, defaults) => {
 	const userConf = conf.get('userconfig');
 
 	if (!conf.get('global') && projectConf !== userConf) {
-		conf.addFile(projectConf, 'project');
+		warnings.push(conf.addFile(projectConf, 'project'));
 	} else {
 		conf.add({}, 'project');
 	}
@@ -45,18 +46,18 @@ module.exports = (opts, types, defaults) => {
 	// than the ones in userconfig
 	if (conf.get('workspace-prefix') && conf.get('workspace-prefix') !== projectConf) {
 		const workspaceConf = path.resolve(conf.get('workspace-prefix'), '.npmrc');
-		conf.addFile(workspaceConf, 'workspace');
+		warnings.push(conf.addFile(workspaceConf, 'workspace'));
 	}
 
-	conf.addFile(conf.get('userconfig'), 'user');
+	warnings.push(conf.addFile(conf.get('userconfig'), 'user'));
 
 	if (conf.get('prefix')) {
 		const etc = path.resolve(conf.get('prefix'), 'etc');
 		conf.root.globalconfig = path.resolve(etc, 'npmrc');
 		conf.root.globalignorefile = path.resolve(etc, 'npmignore');
 	}
 
-	conf.addFile(conf.get('globalconfig'), 'global');
+	warnings.push(conf.addFile(conf.get('globalconfig'), 'global'));
 	conf.loadUser();
 
 	const caFile = conf.get('cafile');
@@ -65,7 +66,10 @@ module.exports = (opts, types, defaults) => {
 		conf.loadCAFile(caFile);
 	}
 
-	return conf;
+	return {
+		config: conf,
+		warnings: warnings.filter(Boolean),
+	};
 };
 
 Object.defineProperty(module.exports, 'defaults', {

lib/conf.js

@@ -44,11 +44,9 @@ class Conf extends ConfigChain {
 			if (error.code === 'ENOENT') {
 				this.add({}, marker);
 			} else {
-				throw error;
+				return `Issue while reading "${file}". ${error.message}`
 			}
 		}
-
-		return this;
 	}
 
 	// https://github.com/npm/cli/blob/latest/lib/config/core.js#L341-L357

test.js

@@ -8,7 +8,7 @@ const m = require('.');
 delete npmDefaults.unicode;
 
 test('mirror npm config', async () => {
-	const conf = m();
+	const { config: conf } = m();
 	const npmConf = await promisify(npmCore.load)();
 
 	expect(conf.globalPrefix).toBe(npmConf.globalPrefix);