fix: ensure undefined options default to an empty object in Server constructor

Author: bjohansebas

lib/Server.js

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

test/e2e/api.test.js

@@ -81,8 +81,17 @@ describe("API", () => {
 
       expect(server.options).toEqual({});
 
-      await server.start();
-      await server.stop();
+      try {
+        await server.start();
+      } finally {
+        await server.stop();
+      }
+    });
+
+    it("should reject `null` options via schema validation", () => {
+      const compiler = webpack(config);
+
+      expect(() => new Server(null, compiler)).toThrow(/Invalid options object/);
     });
   });