test: report actual error code on failure

Add a custom message to parallel/test-dgram-error-message-address so
that the actual error code that doesn't match the allowed errors is
output on assertion failure.

PR-URL: #34134
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Shelley Vohr <codebytere@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Jiawen Geng <technicalcute@gmail.com>

test/parallel/test-dgram-error-message-address.js

@@ -47,7 +47,7 @@ socket_ipv6.on('listening', common.mustNotCall());
 socket_ipv6.on('error', common.mustCall(function(e) {
   // EAFNOSUPPORT or EPROTONOSUPPORT means IPv6 is disabled on this system.
   const allowed = ['EADDRNOTAVAIL', 'EAFNOSUPPORT', 'EPROTONOSUPPORT'];
-  assert(allowed.includes(e.code));
+  assert(allowed.includes(e.code), `'${e.code}' was not one of ${allowed}.`);
   assert.strictEqual(e.port, undefined);
   assert.strictEqual(e.message, `bind ${e.code} 111::1`);
   assert.strictEqual(e.address, '111::1');