Performance failure report prints 'sanity error' which is confusing

This is known "bug" and is due to the fact that mechanism of sanity and performance patterns is the same; the same sanity functions are used in both. The sanity functions always raise a `SanityError` in case of errors, which is reported as "sanity error". We can fix that by reraising sanity errors as a `PerformanceError`, which will be reported differently.