langchain-typesafe: TypeSafeClassifier sends requests when questions is empty

### Submission checklist - [x] This is a bug, not a usage question. - [x] I added a clear and descriptive title that summarizes this issue. - [x] I used the GitHub search to find a similar question and didn't find it. - [x] I am sure that this is a bug in LangChain rather than my code. - [x] The bug is not resolved by updating to the latest stable version of LangChain (or the specific integration package). - [x] This is not related to the langchain-community package. - [x] I posted a self-contained, minimal, reproducible example. A maintainer can copy it and run it AS IS. ### Package (Required) - [ ] langchain - [ ] langchain-openai - [ ] langchain-anthropic - [ ] langchain-classic - [ ] langchain-core - [ ] langchain-model-profiles - [ ] langchain-tests - [ ] langchain-text-splitters - [ ] langchain-chroma - [ ] langchain-deepseek - [ ] langchain-exa - [ ] langchain-fireworks - [ ] langchain-groq - [ ] langchain-huggingface - [ ] langchain-mistralai - [ ] langchain-nomic - [ ] langchain-ollama - [ ] langchain-openrouter - [ ] langchain-perplexity - [ ] langchain-qdrant - [x] langchain-typesafe - [ ] langchain-xai - [ ] Other / not sure / general ### Related Issues / PRs Related to #40659, which moved classifier questions from constructor configuration into each invocation request. ### Reproduction Steps / Example Code (Python) ```python import json import httpx2 from langchain_typesafe import TypeSafeClassifier sent_payloads: list[dict] = [] def handler(request: httpx2.Request) -> httpx2.Response: sent_payloads.append(json.loads(request.content)) return httpx2.Response(200, json={"model": "jev-latest", "answers": {}}) with httpx2.Client(transport=httpx2.MockTransport(handler)) as client: classifier = TypeSafeClassifier(api_key="test-api-key", client=client) classifier.invoke({"state": "Classify this message.", "questions": {}}) print(sent_payloads[0]) ``` ### Error Message and Stack Trace (if applicable) ```shell No exception is raised locally. The …