fix: guard parent access in addTsEsmHook for ESM-to-CJS sub-dependency resolution

.gitignore

@@ -15,5 +15,6 @@
 **/.idea
 
 !test/cli_coverage/node_modules
+!test/cli_typescript_esm_dep/node_modules
 test_runner
 test/cli/test/leaks.js

lib/cli.js

@@ -89,7 +89,7 @@ internals.addTsEsmHook = function () {
 
     Module._resolveFilename = function (request, parent, ...rest) {
 
-        if (request.endsWith('.js') && (parent.filename.endsWith('.ts') || parent.filename.endsWith('.tsx'))) {
+        if (request.endsWith('.js') && parent && (parent.filename.endsWith('.ts') || parent.filename.endsWith('.tsx'))) {
             const target = Path.join(parent.path, request);
             const tsEquivalent = `${target.slice(0, -3)}.ts`;
 

test/cli_typescript_esm_dep/package.json

@@ -0,0 +1 @@
+{ "type": "module" }

test/cli_typescript_esm_dep/simple.ts

@@ -0,0 +1,15 @@
+import { expect } from '@hapi/code';
+import * as _Lab from '../../test_runner/index.js';
+
+import { add } from 'esm-dep';
+
+
+const { describe, it } = exports.lab = _Lab.script();
+
+describe('Test CLI', () => {
+
+    it('imports from an ESM dependency', () => {
+
+        expect(add(1, 1)).to.equal(2);
+    });
+});

test/cli_typescript_esm_dep/tsconfig.json

@@ -0,0 +1,8 @@
+{
+    "compilerOptions": {
+        "target": "es2021",
+        "module": "commonjs",
+        "moduleResolution": "node",
+        "removeComments": true
+    }
+}

test/typescript.js

@@ -4,6 +4,7 @@ const Fs = require('fs');
 const Path = require('path');
 
 const Code = require('@hapi/code');
+const Somever = require('@hapi/somever');
 const _Lab = require('../test_runner');
 const RunCli = require('./run_cli');
 const Ts = require('typescript');
@@ -44,6 +45,15 @@ describe('TypeScript', () => {
         expect(result.output.split('Test duration').length - 1).to.equal(1);
     });
 
+    it('supports TypeScript with ESM dependencies', { skip: !Somever.match(process.version, '>=20') }, async () => {
+
+        process.chdir(Path.join(__dirname, 'cli_typescript_esm_dep'));
+        const result = await RunCli(['simple.ts', '-m', '2000', '--typescript']);
+        expect(result.errorOutput).to.equal('');
+        expect(result.code).to.equal(0);
+        expect(result.output).to.contain('1 tests complete');
+    });
+
     it('handles errors', async () => {
 
         process.chdir(Path.join(__dirname, 'cli_typescript'));