Error BadRequestError: Error code: 400

I sometimes get an error that the content is empty.

chat.toolloop(conversation)

BadRequestError: Error code: 400 - {'type': 'error', 'error': {'type': 'invalid_request_error', 'message': 'messages: text content blocks must be non-empty'}}

In the history:
{'role': 'assistant', 'content': ''},

I'm using
claudette: 0.1.2
AnthropicVertex: 0.43.1

Start by reproducing chat.toolloop(conversation) with the history containing {'role': 'assistant', 'content': ''} under claudette 0.1.2 and AnthropicVertex 0.43.1. Trace how that history reaches the request and verify the empty-content case is handled without producing the reported BadRequestError.

Written by the indexing model from the issue text.