quic: fix error message on invalid connection ID

If Buffer.from() throws, it does not return a value, so the error
message is always going to report `undefined`. Use the value passed to
Buffer.from() instead.

PR-URL: #35026
Reviewed-By: Jiawen Geng <technicalcute@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

lib/internal/quic/util.js

@@ -405,11 +405,11 @@ function validateQuicClientSessionOptions(options = {}) {
     if (typeof dcid_value === 'string') {
       // If it's a string, it must be a hex encoded string
       try {
-        dcid = Buffer.from(dcid_value, 'hex');
+        Buffer.from(dcid_value, 'hex');
       } catch {
         throw new ERR_INVALID_ARG_VALUE(
           'options.dcid',
-          dcid,
+          dcid_value,
           'is not a valid QUIC connection ID');
       }
     }