fix: test for `simple_set` and `simple_set`

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

@@ -225,6 +225,8 @@ export function simple_set(source, value, should_proxy = false, needs_previous =
 
 	source.v = new_value;
 
+	source.o?.onchange?.();
+
 	return new_value;
 }
 

packages/svelte/tests/runtime-runes/samples/state-onchange/main.svelte

@@ -37,7 +37,7 @@
 
 
 		constructor(){
-			this.#in_constructor++;
+			this.#in_constructor = 42;
 			this.#in_constructor_proxy.count++;
 		}
 	}