fix: lazy-load storage cache on set() to prevent null spread (#38)

When an MV3 service worker wakes up and calls set() with an updater
(e.g. requestStorage.addEvent spreading prev into a new array), the
in-memory cache may still be null because _getDataFromStorage() is
async. The updater then runs with prev = null and [...null] throws
"TypeError: a is not iterable", aborting addEvent and leaving the
approval flow in a bad state (popup opens for a request that was
never persisted).

Load the cache synchronously-ish (await from chrome.storage) in set()
if it's still null, so every updater receives a real value.

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: BitHighlander

packages/storage/lib/base.ts

@@ -168,6 +168,9 @@ export function createStorage<D = string>(key: string, fallback: D, config?: Sto
   };
 
   const set = async (valueOrUpdate: ValueOrUpdate<D>) => {
+    if (cache === null) {
+      cache = await _getDataFromStorage();
+    }
     cache = await updateCache(valueOrUpdate, cache);
 
     await chrome.storage[storageType].set({ [key]: serialize(cache) });