From 677a2c259ca50862cbbd4a9cc95c64d810fbcccd Mon Sep 17 00:00:00 2001
From: robobun <117481402+robobun@users.noreply.github.com>
Date: Wed, 11 Nov 2026 07:37:54 +0000
Subject: [PATCH 1/2] Bun.file(fd).delete(): reject instead of resolving with
 the TypeError

The Fd arm of FileExt::unlink built ERR_INVALID_ARG_TYPE and passed it to
JSPromise::resolved_promise_value, so delete() and unlink() on a file made
from a descriptor resolved with the error as their value. The arm now
returns a rejected promise with the same error.
---
 src/runtime/webcore/blob/Store.rs    |  5 +++--
 test/js/web/fetch/blob-write.test.ts | 16 ++++++++++++++++
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/src/runtime/webcore/blob/Store.rs b/src/runtime/webcore/blob/Store.rs
index 15130252fdbc..d3a7ed83c97b 100644
--- a/src/runtime/webcore/blob/Store.rs
+++ b/src/runtime/webcore/blob/Store.rs
@@ -230,7 +230,7 @@ impl FileExt for File {
                     None,
                 ))
             }
-            PathOrFileDescriptor::Fd(_) => Ok(JSPromise::resolved_promise_value(
+            PathOrFileDescriptor::Fd(_) => Ok(JSPromise::rejected_promise(
                 cx.global(),
                 // `JSGlobalObject::create_invalid_args` lives in the still-gated
                 // `JSGlobalObject.rs`; `ERR_INVALID_ARG_TYPE` (lib.rs) is the
@@ -238,7 +238,8 @@ impl FileExt for File {
                 cx.global().ERR_INVALID_ARG_TYPE(format_args!(
                     "Is not possible to unlink a file descriptor"
                 )),
-            )),
+            )
+            .to_js()),
         }
     }
 }
diff --git a/test/js/web/fetch/blob-write.test.ts b/test/js/web/fetch/blob-write.test.ts
index 02d3111eb98b..be10c11fc397 100644
--- a/test/js/web/fetch/blob-write.test.ts
+++ b/test/js/web/fetch/blob-write.test.ts
@@ -1,4 +1,5 @@
 import { expect, test } from "bun:test";
+import { closeSync, openSync } from "fs";
 import { expectMaxObjectTypeCount, tempDir, tempDirWithFiles } from "harness";
 import path from "path";
 
@@ -55,6 +56,21 @@ test("Bun.file(path).delete() does not throw", async () => {
   expect(await Bun.file(path.join(dir, "a")).exists()).toBe(false);
 });
 
+// A file made from a descriptor has no path to unlink.
+test.each(["unlink", "delete"] as const)("Bun.file(fd).%s() rejects", async method => {
+  await using dir = tempDir("bun-unlink-fd", { a: "Hello, world!" });
+  const fd = openSync(path.join(dir, "a"), "r");
+  try {
+    await expect(Bun.file(fd)[method]()).rejects.toMatchObject({
+      code: "ERR_INVALID_ARG_TYPE",
+      message: "Is not possible to unlink a file descriptor",
+    });
+  } finally {
+    closeSync(fd);
+  }
+  expect(await Bun.file(path.join(dir, "a")).exists()).toBe(true);
+});
+
 test("blob.writer() throws for data-backed blob", () => {
   const blob = new Blob(["Hello, world!"]) as any;
   expect(() => blob.writer()).toThrowErrorMatchingInlineSnapshot(

From de58ed4ea3bd926e1aca0bc849fbf55994418c86 Mon Sep 17 00:00:00 2001
From: robobun <117481402+robobun@users.noreply.github.com>
Date: Wed, 11 Nov 2026 07:52:11 +0000
Subject: [PATCH 2/2] test: pin the error class of the Bun.file(fd).delete()
 rejection

---
 test/js/web/fetch/blob-write.test.ts | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/test/js/web/fetch/blob-write.test.ts b/test/js/web/fetch/blob-write.test.ts
index be10c11fc397..2a45f53546af 100644
--- a/test/js/web/fetch/blob-write.test.ts
+++ b/test/js/web/fetch/blob-write.test.ts
@@ -61,7 +61,9 @@ test.each(["unlink", "delete"] as const)("Bun.file(fd).%s() rejects", async meth
   await using dir = tempDir("bun-unlink-fd", { a: "Hello, world!" });
   const fd = openSync(path.join(dir, "a"), "r");
   try {
-    await expect(Bun.file(fd)[method]()).rejects.toMatchObject({
+    const promise = Bun.file(fd)[method]();
+    await expect(promise).rejects.toBeInstanceOf(TypeError);
+    await expect(promise).rejects.toMatchObject({
       code: "ERR_INVALID_ARG_TYPE",
       message: "Is not possible to unlink a file descriptor",
     });