fix(ext/fetch): better error message when body resource is unavailable (#27429)

fixes #27132

When the body resource is unavailable when start reading it, the error
message is `Bad Resource ID` and that doesn't tell what's wrong very
well.

This PR changes that error message to `Cannot read body as underlying
resource unavailable`

ext/fetch/22_body.js

@@ -13,6 +13,7 @@
 
 import { core, primordials } from "ext:core/mod.js";
 const {
+  BadResourcePrototype,
   isAnyArrayBuffer,
   isArrayBuffer,
   isStringObject,
@@ -26,6 +27,7 @@ const {
   JSONParse,
   ObjectDefineProperties,
   ObjectPrototypeIsPrototypeOf,
+  PromisePrototypeCatch,
   TypedArrayPrototypeGetBuffer,
   TypedArrayPrototypeGetByteLength,
   TypedArrayPrototypeGetByteOffset,
@@ -160,7 +162,18 @@ class InnerBody {
       )
     ) {
       readableStreamThrowIfErrored(this.stream);
-      return readableStreamCollectIntoUint8Array(this.stream);
+      return PromisePrototypeCatch(
+        readableStreamCollectIntoUint8Array(this.stream),
+        (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",
+  );
+});