Brummel
9c434fb49d
When a generic function indexes the same TypeVar parameter multiple times, all resulting TypeVars must share a single element type. This change ensures that subsequent indexing operations unify their fresh TypeVar with an existing one if the parameter has already been indexed, preventing incorrect type inference and false negatives. A new test, `test_let_poly_multi_index_all_results_typed`, is added to verify this behavior.