V A L I D A T E

Typical usage:
import Validate from 'rufflib-validate';

function sayOk(n, allowInvalid) {
    const v = new Validate('sayOk()', allowInvalid);
    if (!v.number(n, 'n', 100)) return v.err;
    return 'ok!';
}

sayOk(123); // ok!
sayOk(null); // sayOk(): 'n' is null not type 'number'
sayOk(3); // 'n' 3 is < 100
sayOk(3, true); // ok! (less safe, but faster)