[fix] Add error handling to get_top_hackernews_stories

[lawrence3699]

I noticed get_top_hackernews_stories has no error handling, while its sibling get_user_details in the same file wraps everything in try/except and returns a descriptive error string. When the HN Firebase API is unreachable or returns unexpected data, get_user_details lets the agent explain the problem to the user, but get_top_hackernews_stories just raises an unhandled exception.

There are two concrete failures:

1. API errors go unhandled. If the Firebase API returns an error or times out, the method crashes instead of returning an error string. get_user_details handles this on line 75.

2. Deleted stories crash the loop. The HN API returns null for deleted items (https://hacker-news.firebaseio.com/v0/item/0.json → null). When story_response.json() returns None, story["by"] raises TypeError: 'NoneType' object is not subscriptable. Job postings can also lack a by field, causing KeyError.

Reproduction:

>>> import httpx
>>> httpx.get("https://hacker-news.firebaseio.com/v0/item/0.json").json()
None
>>> None["by"]
TypeError: 'NoneType' object is not subscriptable

The fix adds a try/except matching get_user_details, skips null stories, and uses .get("by", "unknown") instead of direct key access.

Tests added:

• test_get_top_stories_error_handling — API failure returns error string
• test_get_top_stories_null_story_skipped — null items are skipped
• test_get_top_stories_missing_by_field — missing by falls back to "unknown"

All 28 tests pass.

Fixes #7352

• AI-assisted

[github-actions]

PR Triage

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[Copilot]

Pull request overview

This PR adds robust error handling to get_top_hackernews_stories to prevent unhandled exceptions when the Hacker News Firebase API fails or returns unexpected/null story payloads.

Changes:

• Wrap get_top_hackernews_stories in try/except and return a descriptive error string on failure.
• Skip null (deleted) story payloads and safely derive username via story.get("by", "unknown").
• Add unit tests covering API failures, null story skipping, and missing by fallback behavior.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
libs/agno/agno/tools/hackernews.py	Adds exception handling and null/missing-field resilience in top stories fetch.
libs/agno/tests/unit/tools/test_hackernews.py	Adds targeted tests for error handling and edge cases introduced by HN API responses.

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