fixup!

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

Author: bjohansebas

lib/Server.js

@@ -341,7 +341,9 @@ class Server {
    * @param {(Compiler | MultiCompiler)=} compiler compiler, omitted when the server is used as a plugin via `apply()`
    */
   constructor(options, compiler) {
-    options ??= {};
+    if (typeof options === "undefined") {
+      options = {};
+    }
 
     validate(/** @type {Schema} */ (schema), options, {
       name: "Dev Server",