[FIX] store: prevent crash when selector returns null

Because `typeof null === 'object'`.

src/store.ts

@@ -132,7 +132,7 @@ export function useStore(selector, options: SelectorOptions = {}): any {
     __destroy.call(component, parent);
   };
 
-  if (typeof result !== "object") {
+  if (typeof result !== "object" || result === null) {
     return result;
   }
   return new Proxy(result, {