fix another case

Author: dummdidumm

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

@@ -31,23 +31,19 @@ export function store_get(store, store_name, stores) {
 			set(entry.source, undefined);
 			entry.unsubscribe = noop;
 		} else {
-			var initial = true;
+			var is_synchronous_callback = true;
 
 			entry.unsubscribe = subscribe_to_store(store, (v) => {
-				if (initial) {
-					// if the first time the store value is read is inside a derived,
-					// we will hit the `state_unsafe_mutation` error if we `set` the value
+				if (is_synchronous_callback) {
+					// If the first updates to the store value (possibly multiple of them) are synchronously
+					// inside a derived, we will hit the `state_unsafe_mutation` error if we `set` the value
 					entry.source.v = v;
-					initial = false;
 				} else {
 					set(entry.source, v);
 				}
 			});
 
-			// also set initial to false right afterwards in case the store subscription callback is async,
-			// in which case the `state_unsafe_mutation` check is not relevant anymore and we would instead
-			// not get notified of the store value change
-			initial = false;
+			is_synchronous_callback = false;
 		}
 	}
 

packages/svelte/tests/runtime-runes/samples/store-async-first-value/main.svelte

@@ -11,8 +11,9 @@
 		};
 	}
 
-	const value = store();
-	const derivedValue = $derived($value);
+	const value1 = store();
+	const value2 = store();
+	const derivedValue = $derived($value1);
 </script>
 
-{$value} / {derivedValue}
+{$value2} / {derivedValue}

packages/svelte/tests/runtime-runes/samples/store-no-mutation-validation/main.svelte

@@ -1,7 +1,18 @@
-<script> 
-	import { writable } from "svelte/store";
-	let store = writable('store');
-	let name = $derived($store); // store signal is updated during reading this, which normally errors, but shouldn't for stores
+<script>
+	import { writable } from 'svelte/store';
+
+	let store1 = writable('store');
+	let store2 = {
+		subscribe: (cb) => {
+			cb('...');
+			cb('Hello');
+			return () => {};
+		}
+	};
+
+	// store signal is updated during reading this, which normally errors, but shouldn't for stores
+	let name = $derived($store1);
+	let hello = $derived($store2);
 </script>
 
-<h1>Hello {name}</h1>
+<h1>{hello} {name}</h1>