Updated the files.

my-app/node_modules/@schematics/angular/server/files/src/app/app.module.server.ts.template

@@ -0,0 +1,14 @@
+import { NgModule } from '@angular/core';
+import { ServerModule } from '@angular/platform-server';
+
+import { AppModule } from './app.module';
+import { AppComponent } from './app.component';
+
+@NgModule({
+  imports: [
+    AppModule,
+    ServerModule,
+  ],
+  bootstrap: [AppComponent],
+})
+export class AppServerModule {}

my-app/node_modules/@schematics/angular/server/files/src/main.server.ts.template

@@ -0,0 +1 @@
+export { AppServerModule as default } from './app/app.module.server';