fix: keep the stack of fetch errors when __filename is undefined

index-fetch.js

@@ -37,7 +37,7 @@ module.exports.fetch = function fetch (init, options = undefined) {
     if (currentFilename) {
       appendFetchStackTrace(err, currentFilename)
     } else if (err && typeof err === 'object') {
-      Error.captureStackTrace(err, module.exports.fetch)
+      Error.captureStackTrace(err)
     }
     throw err
   })

index.js

@@ -158,7 +158,7 @@ module.exports.fetch = function fetch (init, options = undefined) {
     if (currentFilename) {
       appendFetchStackTrace(err, currentFilename)
     } else if (err && typeof err === 'object') {
-      Error.captureStackTrace(err, module.exports.fetch)
+      Error.captureStackTrace(err)
     }
     throw err
   })

test/fetch/client-error-stack-trace.js

@@ -2,6 +2,9 @@
 
 const { test, after } = require('node:test')
 const { sep, basename, join } = require('node:path')
+const { readFileSync } = require('node:fs')
+const { createRequire } = require('node:module')
+const { runInThisContext } = require('node:vm')
 const { fetch, setGlobalDispatcher, getGlobalDispatcher, Agent } = require('../..')
 
 const projectFolder = basename(join(__dirname, '..', '..'))
@@ -40,3 +43,18 @@ test('FETCH-index: request errors and prints trimmed stack trace', async (t) =>
     t.assert.ok(stackLines.some(line => line.includes(__filename)))
   }
 })
+
+test('FETCH-index: request errors keep their stack trace when __filename is undefined', async (t) => {
+  // Node.js bundles index-fetch.js into a module wrapper without __filename
+  const file = join(__dirname, '..', '..', 'index-fetch.js')
+  const wrapper = runInThisContext(`(function (exports, require, module) {${readFileSync(file, 'utf8')}\n})`, { filename: file })
+  const bundled = { exports: {} }
+  wrapper(bundled.exports, createRequire(file), bundled)
+
+  await t.assert.rejects(bundled.exports.fetch('http://localhost:1'), (error) => {
+    const stackLines = error.stack.split('\n')
+    t.assert.ok(stackLines[0].includes('TypeError: fetch failed'))
+    t.assert.ok(stackLines.some(line => line.includes(__filename)))
+    return true
+  })
+})