## Fix `chat_template` to handle assistant messages without a `content` key
**⚠️ This template will start crashing for every tool-calling user as soon as the next `transformers` release ships.**
The upstream PR https://github.com/huggingface/transformers/pull/45422 normalizes message inputs by stripping `content=None` before rendering (`None` and absent are semantically identical, and `content=None` is exactly what the OpenAI API returns for tool-call-only messages). That normalization is correct, but it exposes a latent bug in this template: the `tool_calls` branch reads `message['content']` directly, which raises when the key is absent.
Concretely, this code path is hit by **any tool-calling pipeline** (OpenAI-compatible servers, agent frameworks, function-calling demos) that produces assistant messages with `tool_calls` and no textual content. Today most of them happen to pass `content=None` explicitly and get away with it. After the transformers release, all of them break.
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