XJS: how to throw error if no match found

I have the following xml file that I am reading via xslt

<root>
      <test>
            <card>VI</card>
            <data>
                  <RegExp>^4[0-9]{12}(?:[0-9]{3})?$</RegExp>
                  <binExp>^[608623]{6}</binExp>
            </data>
      </test>
      <test>
            <card>MC</card>
            <data>
                  <RegExp>(?:^5[1-5]|^2[2-7])[0-9]{14}$</RegExp>
                  <binExp>^[542446]{6}</binExp>
            </data>
      </test>
</root>

Currently, I have logic where if the card number does not satisfy the RegExp then an error is thrown "Number is invalid"

However, I need to change my logic for a special case where if a VI number is entered that fails the RegExp but passes the binExp then DO NOT throw error all while still capturing error for other cards where it throws error if RegExp fails on them.

I had the following logic:

if (cardType != "VI" &&  (binExp && (binExp.test(cardNumber))) ) 
{

      if (RegExp && (!RegExp.test(cardNumber)))
            throw "Number is invalid";                        
      
}

           
but this won't work for an invalid MC. I want it throw error.
Example, I expect
5204730000001003 to pass
5704730000001003 to fail //but my logic doesn't throw error here. when it should.