Fix: The handler returns `None` if JSON parsing fails, but the endpoint signature expects a `BlogTopicIdeasResponse`. Consider returning a proper HTTP error (e.g., `HTTPException`) or a default response to avoid unexpected `null` values.

[cmorman89]

The handler returns None if JSON parsing fails, but the endpoint signature expects a BlogTopicIdeasResponse. Consider returning a proper HTTP error (e.g., HTTPException) or a default response to avoid unexpected null values.

Originally posted by @Copilot in #2 (comment)