fix store set in reactive statement (#380)

Author: jasonlyu123

packages/svelte2tsx/src/svelte2tsx.ts

@@ -770,7 +770,11 @@ function processInstanceScriptContent(str: MagicString, script: Node): InstanceS
                 ts.isIdentifier(node.statement.expression.left)
             ) {
                 const name = node.statement.expression.left.text;
-                if (!implicitTopLevelNames.has(name)) {
+
+                // svelte won't let you create a variable with $ prefix anyway
+                const isPotentialStore = name.startsWith('$');
+
+                if (!implicitTopLevelNames.has(name) && !isPotentialStore) {
                     implicitTopLevelNames.set(name, node.label.getStart());
                 }
 

packages/svelte2tsx/test/svelte2tsx/samples/reactive-store-set/expected.tsx

@@ -0,0 +1,12 @@
+<></>;function render() {
+
+    $: store.set( __sveltets_invalidate(() => __sveltets_store_get(store) + 1));
+;
+() => (<></>);
+return { props: {}, slots: {}, getters: {}, events: {} }}
+
+export default class Input__SvelteComponent_ {
+    $$prop_def = __sveltets_partial(render().props)
+    $$slot_def = render().slots
+    $on = __sveltets_eventDef(render().events)
+}

packages/svelte2tsx/test/svelte2tsx/samples/reactive-store-set/input.svelte

@@ -0,0 +1,3 @@
+<script>
+    $: $store = $store + 1;
+</script>