- Fix setup_llm method to check isinstance(self.llm, BaseLLM) instead of LLM
- Fix ensure_guardrail_is_callable method to check isinstance(self.llm, BaseLLM)
- Add comprehensive test for CustomLLM with guardrails functionality
- Resolves issue #3112 where CustomLLM classes couldn't use guardrails
Co-Authored-By: João <joao@crewai.com>