fix save journal button and reactive city filtering by country

src/lib/stores/entriesStore.svelte.js

@@ -27,7 +27,7 @@ export function initEntriesListener(uid) {
 }
 
 export async function addEntry(data) {
-  if (!_uid) return null;
+  if (!_uid) throw new Error('Not logged in');
   const ref = await addDoc(collection(db, 'users', _uid, 'entries'), {
     ...data,
     createdAt: serverTimestamp(),