Fix: handling verify function edge case

[rafayeljamalyan]

If the verify function is created using rest params, the length of that function (arity) will be 0, so we need to handle that case.
I faced this issue when using this package along with Nest.JS, where verify callback is created using rest params.

...
const callback = (...params) => __awaiter(this, void 0, void 0, function* () {
const done = params[params.length - 1];
    try {
        const validateResult = yield this.validate(...params);  /* here this.validate is our verify callback */
        if (Array.isArray(validateResult)) {
            done(null, ...validateResult);
        }
        else {
            done(null, validateResult);
        }
    }
    catch (err) {
        done(err, null);
    }
});
            ...