chore: add nullable

app/.expo-shared/README.md

@@ -0,0 +1,11 @@
+> Why do I have a folder named ".expo-shared" in my project?
+
+The ".expo-shared" folder is created when running commands that produce state that is intended to be shared with all developers on the project. For example, "npx expo-optimize".
+
+> What does the "assets.json" file contain?
+
+The "assets.json" file describes the assets that have been optimized through "expo-optimize" and do not need to be processed again.
+
+> Should I commit the ".expo-shared" folder?
+
+Yes, you should share the ".expo-shared" folder with your collaborators.

app/src/services/Firebase.js

@@ -30,7 +30,7 @@ class FirebaseService {
     }
 
     async getUserId() {
-        return await this.firebase.auth().currentUser.getIdToken();
+        return await this.firebase.auth().currentUser?.getIdToken();
     }
     async getCurrentUser() {
         return this.firebase.auth().currentUser;