show alert when no signing method is found

lib/utils.ts

@@ -57,7 +57,12 @@ export async function signEvent(loginType: string | null, event: NostrEvent): Pr
       }
     }
   } else {
+    if(window.nostr) { 
       eventSigned = await window.nostr.signEvent(event);
+    } else {
+      alert('No signing method found.')
+      return null;
+    }
   }
   console.log(eventSigned);
   return eventSigned;