fs: avoid unhandled rejection in filehandle readableWebStream close

lib/internal/fs/promises.js

@@ -335,7 +335,11 @@ class FileHandle extends EventEmitter {
     } = require('internal/webstreams/readablestream');
     this[kRef]();
     this.once('close', () => {
-      readableStreamCancel(readable);
+      PromisePrototypeThen(
+        readableStreamCancel(readable),
+        undefined,
+        () => undefined,
+      );
     });
 
     return readable;

test/parallel/test-filehandle-readablestream-error-close.js

@@ -0,0 +1,82 @@
+'use strict';
+
+const common = require('../common');
+const assert = require('assert');
+
+async function runScript(source) {
+  const child = await common.spawnPromisified(process.execPath, [
+    '--unhandled-rejections=strict',
+    '-e',
+    source,
+  ]);
+
+  assert.strictEqual(child.code, 0, child.stderr);
+  assert.strictEqual(child.signal, null);
+  assert.strictEqual(child.stderr, '');
+}
+
+// Regression: once a readableWebStream read fails, explicitly closing the
+// FileHandle must not trigger an unhandled rejection.
+(async () => {
+  await runScript(`
+    const { closeSync } = require('node:fs');
+    const { open } = require('node:fs/promises');
+    const assert = require('node:assert');
+
+    async function consume(readable) {
+      for await (const _ of readable);
+    }
+
+    (async () => {
+      const file = await open(process.execPath);
+      const readable = file.readableWebStream();
+      closeSync(file.fd);
+
+      await assert.rejects(consume(readable), { code: 'EBADF' });
+      await assert.rejects(file.close(), { code: 'EBADF' });
+    })().catch((err) => {
+      console.error(err);
+      process.exitCode = 1;
+    });
+  `);
+})().then(common.mustCall());
+
+// Edge: BYOB readers should not leak unhandled rejections on the same path.
+(async () => {
+  await runScript(`
+    const { closeSync } = require('node:fs');
+    const { open } = require('node:fs/promises');
+    const assert = require('node:assert');
+
+    (async () => {
+      const file = await open(process.execPath);
+      const readable = file.readableWebStream();
+      const reader = readable.getReader({ mode: 'byob' });
+      closeSync(file.fd);
+
+      await assert.rejects(reader.read(new DataView(new ArrayBuffer(1024))), {
+        code: 'EBADF',
+      });
+      await assert.rejects(file.close(), { code: 'EBADF' });
+    })().catch((err) => {
+      console.error(err);
+      process.exitCode = 1;
+    });
+  `);
+})().then(common.mustCall());
+
+// Safety: successful reads must remain unaffected.
+(async () => {
+  await runScript(`
+    const { open } = require('node:fs/promises');
+
+    (async () => {
+      const file = await open(process.execPath);
+      for await (const _ of file.readableWebStream());
+      await file.close();
+    })().catch((err) => {
+      console.error(err);
+      process.exitCode = 1;
+    });
+  `);
+})().then(common.mustCall());