typeof returns type name as string

fix checking of window for SSR.

index.js

@@ -3,15 +3,15 @@ import { writable } from 'svelte/store';
 let prefix = 'svelteStore';
 
 const get = (key) => {
-  if (typeof window === undefined || !localStorage) return undefined;
+  if (typeof window === 'undefined' || !window.localStorage) return;
   const value = localStorage.getItem(key);
   return value === undefined
     ? ""
     : JSON.parse(value);
 };
 
 const set = (key, value) => {
-  if (typeof window === undefined || !localStorage) return;
+  if (typeof window === 'undefined' || !window.localStorage) return;
 
   localStorage.setItem(key, JSON.stringify(value));
 };
@@ -37,4 +37,4 @@ export const syncable = (name, value, hydrate = true) => {
   }
 
   return syncValue(key, writable(lastValue));
-};
+};