Revert "Use null as fallback password"

This reverts commit ce9c6490.

js/src/components/P12Download.jsx

@@ -21,7 +21,7 @@ const P12Download = ({privateKey, certPems, password}) => {
           return
       }
       const p12Asn1 = pkcs12.toPkcs12Asn1(
-        privateKey, cert, password || null,
+        privateKey, cert, password,
         {algorithm: '3des'}
       )
       const p12 = asn1.toDer(p12Asn1).getBytes()