fix: page may fail to load due to shortcut links function failing

src/SEQTA.ts

@@ -2420,7 +2420,12 @@ export async function loadHomePage() {
   const cleanup = setupTimetableListeners()
 
   // Initialize shortcuts immediately
-  addShortcuts(settingsState.shortcuts)
+  try {
+    addShortcuts(settingsState.shortcuts)
+  } catch(err: any) {
+    console.error('[BetterSEQTA+] Error adding shortcuts:',
+      err.message || err)
+  }
   AddCustomShortcutsToPage()
 
   // Get current date

src/types/storage.ts

@@ -39,6 +39,7 @@ export interface SettingsState {
   devMode?: boolean;
   originalDarkMode?: boolean;
   assessmentsAverage?: boolean;
+  lettergrade: boolean;
 }
 
 interface ToggleItem {