llm: fix panic on missing required fields

[gioelecerati]

What does this pull request do? Explain your changes. (required)

Specific updates (required)

• Added a check for the required fields on the LLM handler to avoid panics

How did you test each of these updates (required)

Does this pull request close any open issues?

Checklist:

• [ ] Read the contribution guide
• [X] make runs successfully
• [X] All tests in ./test.sh pass
• [ ] README and other documentation updated
• [ ] Pending changelog updated