5fbc73269f
Refactor the formula parser to assume grammar invariants, replacing Result-based error handling in tree walkers with infallible functions and .expect(GRAMMAR_INVARIANT) calls. This simplification is based on the guarantee that the Pest grammar already validates the input structure. To verify these invariants and ensure correctness, extensive new unit tests and property-based tests using proptest have been added. Co-Authored-By: fiddlerwoaroof/git-smart-commit (gemma-4-31B-it-UD-Q4_K_XL.gguf)