$$ User Authentication: You have to write an advanced java script code for the function signIn$().$

$$ This function designs a sign$-$in functionality where registered users can log in with their username and password.

$$ Validates user credentials against the stored user data.

$$ Implements session management using session storage upon successful login to maintain the user's login status.

$$ Implements error handling for incorrect login credentials or any unexpected issues during data fetching or processing.

$$ Provides informative error messages to guide users in case of registration or login failures