Add onError handler to useAssistant hook

[mfts]

similar to useChat exposing an onError handler on the useAssistant hook.

const { status, messages, input, submitMessage, handleInputChange, error } =
    useAssistant({
      api: '/api/assistant',
      onError: err => { 
        console.error(err.message);
      },
    });

[lgrammel]

Thanks, this looks great!

[lgrammel]

Build failure seems to be related to changes in PR.

[mfts]

Build failure seems to be related to changes in PR.

Sorry for the slow response. I created a proper Error and passed it in. That should fix the issue.

[mfts]

fixed the prettier format error

[MaxLeiter]

Thanks @mfts! Can you update the OptionTable in docs/pages/docs/api-reference/use-assistant.mdx?

[mfts]

Added documentation