Describe the bug

When streaming an agent response using the completions API with an Azure OpenAI endpoint, prompt annotations are returned from the model where the choices propery is []. The following code does not adequately handle a choices property that exists, but contains no elements:

        if (!chunk.choices || !chunk.choices[0].delta)
            continue;

This results in a Cannot read properties of undefined (reading 'delta') error.

Debug information

• Agents SDK version: (e.g. v0.0.7)
• Runtime environment (e.g. Node.js 22.16.0)

Repro steps

Use an Azure OpenAI endpoint with any prompt and the following set:

setOpenAIAPI('chat_completions');
const stream = await runner.run(agent, messages, {
      stream: true,
    });

Expected behavior

At a minimum, the prompt annotations should be ignored and the streamed chat completion should resume.