fix: Prevent TypeError from caching API error responses

[sentry]

This PR addresses a TypeError: .map is not a function occurring in getComponents (and potentially getFlags) when the Codecov browser extension attempts to process cached API responses.

Root Cause:
Previously, src/service.ts unconditionally cached API responses, including error objects (e.g., JSON bodies from 404, 403, or 429 HTTP statuses). When these cached error objects were retrieved, they were returned with ok: true, leading src/content/github/common/fetchers.ts to incorrectly assume the response.data was an array and attempt to call .map() on it, resulting in the TypeError.

Solution:

1. Prevent caching of error responses: In src/service.ts, the calls to setCached within listFlags and listComponents are now guarded by response.ok. This ensures that only successful API responses are stored in the cache, preventing error objects from being treated as valid data.
2. Defense-in-depth with Array.isArray() checks: In src/content/github/common/fetchers.ts, Array.isArray() checks have been added before calling .map() in both getComponents and getFlags. This provides an additional layer of protection, ensuring that .map() is only ever called on actual arrays, even if a non-array value were to somehow reach these functions.

This fix aligns with the proposed solution in PR #164.

Fixes BROWSER-EXTENSION-DW

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[codecov]

Bundle Report

Changes will increase total bundle size by 149 bytes (0.02%) ⬆️. This is within the configured threshold ✅

Detailed changes

Bundle name	Size	Change
codecov-browser-extension-array-push	660.61kB	149 bytes (0.02%) ⬆️

Affected Assets, Files, and Routes:

view changes for bundle: codecov-browser-extension-array-push

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
background.js	101 bytes	207.76kB	0.05%
githubFile.js	48 bytes	11.51kB	0.42%

Files in githubFile.js:

• ./src/content/github/common/fetchers.ts → Total Size: 2.55kB