fix(ext/fetch): better error message when body resource is unavailable

ext/fetch/22_body.js

@@ -13,6 +13,7 @@
 
 import { core, primordials } from "ext:core/mod.js";
 const {
+  BadResourcePrototype,
   isAnyArrayBuffer,
   isArrayBuffer,
   isStringObject,
@@ -160,7 +161,15 @@ class InnerBody {
       )
     ) {
       readableStreamThrowIfErrored(this.stream);
-      return readableStreamCollectIntoUint8Array(this.stream);
+      return readableStreamCollectIntoUint8Array(this.stream).catch((e) => {
+        if (ObjectPrototypeIsPrototypeOf(BadResourcePrototype, e)) {
+          // TODO(kt3k): We probably like to pass e as `cause` if BadResource supports it.
+          throw new e.constructor(
+            "Cannot read body as underlying resource unavailable",
+          );
+        }
+        throw e;
+      });
     } else {
       this.streamOrStatic.consumed = true;
       return this.streamOrStatic.body;

tests/unit/body_test.ts

@@ -1,5 +1,5 @@
 // Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
-import { assert, assertEquals } from "./test_util.ts";
+import { assert, assertEquals, assertRejects } from "./test_util.ts";
 
 // just a hack to get a body object
 // deno-lint-ignore no-explicit-any
@@ -187,3 +187,14 @@ Deno.test(
     assertEquals(file.size, 1);
   },
 );
+
+Deno.test(async function bodyBadResourceError() {
+  const file = await Deno.open("README.md");
+  file.close();
+  const body = buildBody(file.readable);
+  await assertRejects(
+    () => body.arrayBuffer(),
+    Deno.errors.BadResource,
+    "Cannot read body as underlying resource unavailable",
+  );
+});