feat: handle zod parse errors by using safeParse

If there is an existing localStorage entry for `key`, the library should
not throw an error, but replace the existing `localStorage` entry with
the `initialValue`.

This allows users of this library to modify stores with new schemas with
ease.

Author: sebastinez

src/index.ts

@@ -39,14 +39,14 @@ export default function storedWritable<
           return;
         }
 
-        w.set(schema.parse(JSON.parse(event.newValue)));
+        const { success, data } = schema.safeParse(JSON.parse(event.newValue));
+        w.set(success ? data : initialValue);
       }
     });
   }
 
-  const w = writable<S>(
-    stored ? schema.parse(JSON.parse(stored)) : initialValue
-  );
+  const parsed = stored ? schema.safeParse(JSON.parse(stored)) : null;
+  const w = writable<S>(parsed?.success ? parsed.data : initialValue);
 
   /**
    * Set writable value and inform subscribers. Updates the writeable's stored data in