fix hoisting of imported, mutated stores (#5022)

src/compiler/compile/Component.ts

@@ -1152,7 +1152,9 @@ export default class Component {
 			for (const specifier of specifiers) {
 				const variable = var_lookup.get(specifier.local.name);
 
-				if (!variable.mutated) variable.hoistable = true;
+				if (!variable.mutated || variable.subscribable) {
+					variable.hoistable = true;
+				}
 			}
 		}
 	}

test/runtime/samples/store-imports-hoisted/_config.js

@@ -0,0 +1,7 @@
+export default {
+	compileOptions: { dev: true }, // tests `@validate_store` code generation
+
+	html: `
+		<p>42</p>
+	`
+};

test/runtime/samples/store-imports-hoisted/foo.js

@@ -0,0 +1,3 @@
+import { writable } from '../../../../store';
+
+export default writable(42);

test/runtime/samples/store-imports-hoisted/main.svelte

@@ -0,0 +1,7 @@
+<script>
+	import foo from './foo.js';
+	foo.bar = 'baz';
+	const answer = $foo;
+</script>
+
+<p>{answer}</p>