Checks if properties can be read off of the input at all.
This exists instead of check.hasKey because check.hasKey costs roughly a microsecond per call
(it runs its attempts through a try/catch), and the predicates below run on every
interpolated value of every template on every render.
Checks if properties can be read off of the input at all.
This exists instead of
check.hasKeybecausecheck.hasKeycosts roughly a microsecond per call (it runs its attempts through atry/catch), and the predicates below run on every interpolated value of every template on every render.