net: use missing validator

The `net` lib module's `lookupAndConnect()` function is missing
a validator.

PR-URL: #38984
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Zijian Liu <lxxyxzj@gmail.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Zeyu Yang <himself65@outlook.com>

lib/net.js

@@ -102,6 +102,7 @@ const {
 const { isUint8Array } = require('internal/util/types');
 const {
   validateAbortSignal,
+  validateFunction,
   validateInt32,
   validateNumber,
   validatePort,
@@ -1002,10 +1003,8 @@ function lookupAndConnect(self, options) {
     return;
   }
 
-  if (options.lookup && typeof options.lookup !== 'function')
-    throw new ERR_INVALID_ARG_TYPE('options.lookup',
-                                   'Function', options.lookup);
-
+  if (options.lookup !== undefined)
+    validateFunction(options.lookup, 'options.lookup');
 
   if (dns === undefined) dns = require('dns');
   const dnsopts = {