fix: handle undefined options in Server constructor

Author: bjohansebas

lib/Server.js

@@ -337,10 +337,12 @@ const pluginName = "webpack-dev-server";
  */
 class Server {
   /**
-   * @param {Configuration<A, S>} options options
+   * @param {Configuration<A, S> | undefined} options options
    * @param {(Compiler | MultiCompiler)=} compiler compiler, omitted when the server is used as a plugin via `apply()`
    */
   constructor(options, compiler) {
+    options ??= {};
+
     validate(/** @type {Schema} */ (schema), options, {
       name: "Dev Server",
       baseDataPath: "options",

test/e2e/api.test.js

@@ -74,6 +74,18 @@ describe("API", () => {
     });
   });
 
+  describe("constructor options", () => {
+    it("should default `undefined` options to `{}`", async () => {
+      const compiler = webpack(config);
+      const server = new Server(undefined, compiler);
+
+      expect(server.options).toEqual({});
+
+      await server.start();
+      await server.stop();
+    });
+  });
+
   describe("latest async API", () => {
     it("should work with async API", async (t) => {
       const compiler = webpack(config);

types/lib/Server.d.ts

@@ -1495,11 +1495,11 @@ declare class Server<
    */
   private static isWebTarget;
   /**
-   * @param {Configuration<A, S>} options options
+   * @param {Configuration<A, S> | undefined} options options
    * @param {(Compiler | MultiCompiler)=} compiler compiler, omitted when the server is used as a plugin via `apply()`
    */
   constructor(
-    options: Configuration<A, S>,
+    options: Configuration<A, S> | undefined,
     compiler?: (Compiler | MultiCompiler) | undefined,
   );
   compiler: