🧪 Add error path test for Canvas crawler fetch failure

[savvides]

🎯 What: Adds a missing Error Path Test for crawlCanvasCourse fetch failure in test/test-crawler.js.
📊 Coverage: The test mocks a failed fetch request (e.g. ok: false with a 404 status) when fetching course information, ensuring the error is thrown properly and matches the expected format Failed to fetch Canvas course info (404).
✨ Result: Better test coverage ensuring stability and expected error-throwing behavior when handling Canvas API failures.

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PR created automatically by Jules for task 10001256865388728052 started by @savvides

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