SearchApi tools - return error message instead of an error.

[SebastjanPrachovskij]

Summary

Instead of raising a ValueError with the message Got error from SearchApi: {res['error']}, the SearchApi now directly returns the res['error'] message. This message provides more specific information, such as YouTube Transcripts didn't return any results.. This change was implemented in response to customer complaints.

Checklist

Important

Please review the checklist below before submitting your pull request.

• This change requires a documentation update, included: Dify Document
• I understand that this PR may be closed in case there was no previous discussion or issues. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.
• I ran dev/reformat(backend) and cd web && npx lint-staged(frontend) to appease the lint gods