Admits undefined and false in place of a validator, so a check may be switched off inline with a guard
expression (enabled && check()) rather than by rebuilding the surrounding composition conditionally. A validator
left out this way is ignored and never contributes to the reported trace.
Optional validator.
Admits
undefinedandfalsein place of a validator, so a check may be switched off inline with a guard expression (enabled && check()) rather than by rebuilding the surrounding composition conditionally. A validator left out this way is ignored and never contributes to the reported trace.