v3

src/app.d.ts

@@ -1,10 +1,13 @@
-/// <reference types="@sveltejs/kit" />
-
 // See https://kit.svelte.dev/docs/types#app
 // for information about these interfaces
-declare namespace App {
-	// interface Locals {}
-	// interface Platform {}
-	// interface Session {}
-	// interface Stuff {}
+// and what to do when importing types
+declare global {
+	namespace App {
+		// interface Error {}
+		// interface Locals {}
+		// interface PageData {}
+		// interface Platform {}
+	}
 }
+
+export {};