docs(learn): correct another example code for the consumption of response body

[tenkirin]

Description

Docs, fix #8331.

Added await response.body?.cancel(); to explicitly destroy the response body before throwing an error.

  if (!response.ok || !response.body) {
+    // consuming the response body is mandatory: https://undici.nodejs.org/#/?id=garbage-collection
+    await response.body?.cancel();
    throw new Error(`Failed to fetch ${url}. Status: ${response.status}`);
  }

Validation

Check List

• I have read the Contributing Guidelines and made commit messages that follow the guideline.
• I have run pnpm format to ensure the code follows the style guide.
• I have run pnpm test to check if all tests are passing.
• I have run pnpm build to check if the website builds without errors.
• I've covered new added functionality with unit tests if necessary.

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Project	Deployment	Preview	Updated (UTC)
nodejs-org	Ready	Preview	Nov 5, 2025 9:50am

[avivkeller]

Thanks! In the future, there's no need to open an issue for these little things. In fact, if you want, you can also group them all into a single PR.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 76.74%. Comparing base (9fbb9f6) to head (e4d7028).
⚠️ Report is 4 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8332      +/-   ##
==========================================
+ Coverage   76.72%   76.74%   +0.02%     
==========================================
  Files         118      118              
  Lines        9805     9805              
  Branches      335      335              
==========================================
+ Hits         7523     7525       +2     
+ Misses       2280     2278       -2     
  Partials        2        2              

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