Add exception handling to the Question Classifier

[bighamx]

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1. Is this request related to a challenge you're experiencing? Tell me about your story.

When using some models, such as Qwen2.5-7/14/32B-Instruct, some question do not output any response:
Run failed: could not find json block in the output.

We can add exception handling to the question classifier, or add a default classification

2. Additional context or comments

No response

3. Can you help us with this feature?

• I am interested in contributing to this feature.