D011 contract_evaluation_failed
Evaluating a contract predicate itself defected (for example it overflowed).
A runtime defect: the running program stops with it; no compile phase reports it, and try cannot catch it. sakura explain D011 prints this explanation offline.
Evaluating a contract predicate itself defected (for example it overflowed). Make the predicate total over every input it can see: compare before multiplying, or bound the operands in the parameter's refined type.
Runtime defects come from running programs, so compiler/tests/ui has no fixture for them; the explanation above names the repair.