[Vercel AI SDK] Formatted messages are not compatible with streamText and other methods

[Dam-Buty]

Consider the following code :

const prompt = await literalAiClient.api.getPrompt("chat")

const messages = prompt.formatMessages({
  // ... some variables here
})

const result = await vercelClient.streamText({
  messages,
  // ... some other settings here
})

This gets the following compile error :

Type '(CoreMessage | ChatCompletionMessageParam)[]' is not assignable to type 'CoreMessage[] | UIMessage[] | undefined'.

Using AI SDK's convertToCoreMessages doesn't seem to solve the issue.