fix: make validateTypes() and safeValidateTypes() async

[gr2m]

Background

Towards #5766

Tasks

• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)
• If required, a patch changeset for relevant packages has been added
• You've run pnpm prettier-fix to fix any formatting issues

[gr2m]

Instead of passing an outputResolver() callback, the output needs to be computed ahead of instantiating the DefaultGenerateTextResult class, in order to retain the synchronous .experimental_output getter API

[gr2m]

To keep track, here are the methods that were previously sync and are now async:

• processResult in packages/ai/core/generate-object/generate-object.ts
• validatePartialResult and validateFinalResult in packages/ai/core/generate-object/output-strategy.ts
• parsePartial and parseOutput in packages/ai/core/generate-text/output.ts
• transform in packages/ai/core/generate-text/stream-text.ts
• parsePartialJson in packages/ai/core/util/parse-partial-json.ts
• onToolCallDeltaPart in packages/ai/core/util/process-chat-response.ts
• doGenerate and doStream in packages/amazon-bedrock/src/bedrock-chat-language-model.ts
• extractMetadata and processChunk in packages/deepseek/src/deepseek-metadata-extractor.ts
• doGenerate and doStream in packages/groq/src/groq-chat-language-model.ts
• doGenerate and doStream in packages/mistral/src/mistral-chat-language-model.ts
• doGenerate and doStream in packages/openai/src/openai-chat-language-model.ts
• doGenerate and doStream in packages/openai/src/responses/openai-responses-language-model.ts
• standardizePrompt in packages/ai/core/prompt/standardize-prompt.ts
• parseJSON and safeParseJSON in packages/provider-utils/src/parse-json.ts
• parseProviderOptions in packages/provider-utils/src/parse-provider-options.ts
• createJsonResponseHandler in packages/provider-utils/src/response-handler.ts

[lgrammel]

Can this error be removed?

[lgrammel]

null output might be valid in some cases. We can remove the error imo

[lgrammel]

(this was the original reason for delaying the check)

[gr2m]

removing the handling of falsy values leads to a type error. The generateText() method could in theory end up returning null or undefined. Shall we update the type?

packages/ai/core/generate-text/generate-text.ts:243:3 - error TS2322: Type 'DefaultGenerateTextResult<TOOLS, Awaited<OUTPUT> | undefined>' is not assignable to type 'GenerateTextResult<TOOLS, OUTPUT>'.
  Types of property 'experimental_output' are incompatible.
    Type 'Awaited<OUTPUT> | undefined' is not assignable to type 'OUTPUT'.
      'OUTPUT' could be instantiated with an arbitrary type which could be unrelated to 'Awaited<OUTPUT> | undefined'.

243   return recordSpan({
      ~~~~~~

[lgrammel]

let's create a ticket to revisit this later

[lgrammel]

Close/re-open to trigger actions.