Identify and prevent code-breaking inputs

Identify inputs and scenarios that could break your implementation and explain how you would prevent them. Consider null or empty inputs, invalid directions or coordinates, out-of-bounds indices, integer overflows, malformed food lists, and duplicate or conflicting constraints. Propose an input-validation strategy, error-handling policy, and a set of unit and property-based tests to catch these cases early. Discuss the trade-offs between defensive checks and runtime performance in production code.