feat: auto create empty schedule when deleted all schedules (#552)

* feat: enhance schedule deletion to create a new schedule if none remain

* feat: set active index to new schedule if only one exists

* chore: run lint

* feat: enhance schedule deletion to create a new schedule if none remain

* feat: set active index to new schedule if only one exists

* chore: run lint

* feat: reset schedules on update, refactor invariant to within deleteSchedule

* chore: pnpm lint

---------

Co-authored-by: Samuel Gunter <29130894+Samathingamajig@users.noreply.github.com>
Co-authored-by: Samuel Gunter <sgunter@utexas.edu>

src/pages/background/events/onUpdate.ts

@@ -1,4 +1,7 @@
 import { ExtensionStore } from '@shared/storage/ExtensionStore';
+import { UserScheduleStore } from '@shared/storage/UserScheduleStore';
+
+import createSchedule from '../lib/createSchedule';
 
 /**
  * Called when the extension is updated (or when the extension is reloaded in development mode)
@@ -8,4 +11,11 @@ export default async function onUpdate() {
         version: chrome.runtime.getManifest().version,
         lastUpdate: Date.now(),
     });
+
+    const schedules = await UserScheduleStore.get('schedules');
+
+    // By invariant, there must always be at least one schedule
+    if (schedules.length === 0) {
+        createSchedule('Schedule 1');
+    }
 }