onError callback is not working since upgrade to v4

[Praneeth-Pike]

since upgrading to v4, my useChat hook is no longer displaying the error. Is anyone else seeing this?

Here's my useChatHook:

const { messages, input, setInput, handleSubmit, isLoading, stop, error } =
		useChat({
			id,
			api: i`${EXPRESS_API_URL}/chat`,
			initialMessages: data.messages,
			onError: (error) => {
				console.error('error on chat', error)
			},
			onFinish: async (message, { finishReason, usage }) => {
                                console.log("onFinish", message.id, finishReason, usage)
			},
		})

and I'm using a express endpoint as the api endpoint:

expressApp.post('/chat', async (req: Request, res: Response) => {
	try {
		const { messages, apiKey, languageModel, context } = req.body

		const model = providerRegistry({
			openaiApiKey: apiKey,
			anthropicApiKey: apiKey,
			googleApiKey: apiKey,
			perplexityApiKey: apiKey,
			xaiApiKey: apiKey,
		}).languageModel(languageModel)

		//console.log('model constructed:', model)
		log.debug('model', model.modelId)
		log.debug('messages', messages.length)
		log.debug('context', context.length)
		//console.log('files', JSON.stringify(files, null, 2))

		const payload = {
			model,
			messages: convertToCoreMessages([
				{
					role: 'system',
					content: context
						? `<MetaPrompt>${ChatSystemPrompt}</MetaPrompt>\n<PreviousContext>${context}</PreviousContext>`
						: `<MetaPrompt>${ChatSystemPrompt}</MetaPrompt>`,
				},
				...messages,
			]),
		}

		const result = streamText({
			...payload,
		})

		return result.pipeDataStreamToResponse(res, {
			sendUsage: true,
			getErrorMessage: (error) => {
				return error instanceof APICallError
					? error.message
					: 'Unknown error'
			},
		})
	} catch (error: any) {
		log.error('Error in /chat:', error)
		res.status(500).json({
			error: error.message ?? 'Internal server error',
		})
	}
})

The same setup was throwing the error to the useChat hook and it was able to display the error message on the front end.