Ignore empty messages

[CyanideByte]

Describe the changes you have made:

• Prevents LLM from responding to the user pressing enter without typing anything.

Reference any relevant issues (e.g. "Fixes #000"):

Fixes https://github.com/OpenInterpreter/open-interpreter/issues/1199

Pre-Submission Checklist (optional but appreciated):

• [x] I have included relevant documentation updates (stored in /docs)
• [x] I have read docs/CONTRIBUTING.md
• [x] I have read docs/ROADMAP.md

OS Tests (optional but appreciated):

• [x] Tested on Windows
• [ ] Tested on MacOS
• [ ] Tested on Linux