Apply a consistent null/empty handling pattern for configuration and user-provided values: - Treat “present but empty” inputs (e.g., env vars set to `""`) as invalid rather than silently falling back. Prefer behavior that surfaces a clear configuration error. - Guard nullable/optional values before use (including `None` from prompt/selection flows). Fail gracefully and consistently. - Normalize user input (e.g., `strip()`), validate required fields, and handle the empty/None case explicitly. - Add tests for failure paths (null/empty inputs) to prevent regressions. Example pattern: ```python import os # 1) Empty env values should not silently fall back base_url = os.environ.get("OLLAMA_BASE_URL", "http://localhost:11434/v1") # If base_url is "", downstream will raise a clear configuration error. # 2) Guard nullable/custom inputs value = prompt_fn() # may return None or "" if value is None: # graceful exit / clear error raise ValueError("Missing model name") model = value.strip() if not model: raise ValueError("Please enter a model name.") # 3) In tests, assert error behavior for None/empty cases ``` This prevents “quiet localhost” (or other misleading defaults) and ensures null/empty misconfigurations are visible, handled safely, and protected by test coverage.