fix: account for mutations in script module in ownership check (#14253)

.changeset/good-laws-sin.md

@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: account for mutations in script module in ownership check

packages/svelte/src/internal/client/dev/ownership.js

@@ -59,6 +59,9 @@ export function get_component() {
 		}
 
 		for (const module of modules) {
+			if (module.end == null) {
+				return null;
+			}
 			if (module.start.line < entry.line && module.end.line > entry.line) {
 				return module.component;
 			}

packages/svelte/tests/runtime-runes/samples/mutate-state-in-context-dev/_config.js

@@ -0,0 +1,7 @@
+import { test } from '../../test';
+
+export default test({
+	compileOptions: {
+		dev: true
+	}
+});

packages/svelte/tests/runtime-runes/samples/mutate-state-in-context-dev/main.svelte

@@ -0,0 +1,6 @@
+<script module>
+	let obj = $state({});
+	obj.test = "hi!";
+</script>
+
+<h1>Values: {JSON.stringify(obj)}</h1>