tidy

packages/svelte/src/internal/client/reactivity/deriveds.js

@@ -124,13 +124,8 @@ export function async_derived(fn, location) {
 
 		if (DEV) current_async_effect = null;
 
-		promise =
+		var r = () => p;
-			prev === null
+		promise = prev?.then(r, r) ?? Promise.resolve(p);
-				? Promise.resolve(p)
-				: prev.then(
-						() => p,
-						() => p
-					);
 
 		prev = promise;