Exercises G21

Description
The app crashes when user try to log in after providing credentials.This issue exists even after restarting the app.
Steps to Reproduce

1. Launch the mobile app.
2. Browse through the app without being logged in.
3. Attempt to write a comment on an article.
4. Click on the login button.
5. Provide valid login credentials.
6. Click on the "Log In" button.
7. The app crashes.
8. Restart the app.
9. Attempt to log in again.
10. The app crashes consistently.
    Expected Result
    After providing valid login credentials and clicking on the "Log in" button the app should log in the user and allow to proceed with writing comments.
    Actual Result
    The app crashes immediately upon clicking on the "Log In" button (after providing valid credentials). The crashing behavior exists even after restarting the app and attempting to log in again.