Warning: Trying to access array offset on value of type bool (PDO)

Question

I don't know why this errors is popping out. This occur when I switch to PDO note: I'm still new to PDO.

Warning: Trying to access array offset on value of type bool in C:\xampp\htdocs\AR NEW\includes\functions.inc.php on line 283

Warning: Trying to access array offset on value of type bool in C:\xampp\htdocs\AR NEW\includes\nav.php on line 29

This is the code for functions.inc.php line 283:

function isAdmin(){
if (isset($_SESSION['user']) && $_SESSION['user']['user_type'] == 'admin' ) {
    return true;
}else{
    return false;
}

}

and this is the code for nav.php line 29

        <?php  if (isset($_SESSION['user'])) : ?>
        <style>nav .logedin{display:block}nav .navbar-animate li a{ 
        padding: 5px 0 0 45px;} 
        </style>
        <! --This is the line 29 --!><li class="username" ><p>Welcome, <? 
        php echo 
         $_SESSION['user'] 
         ['username']; ?> 
        </p></li>
        <li><a class="logout" href="index.php?logout='1'">logout</a></li>
        <?php elseif($page=='about'): ?>
        <li><a href="signup.php" class="lgin">Signup</a></li>
        <?php else: ?>
        <li><a href="index.php" class="lgin">Login</a></li>
        <?php endif ?>

Here's the whole code for reggister:

     // register user if there are no errors in the form
    if (count($errors) == 0) {


    if (isset($_POST['user_type'])) {
        $user_type = e($_POST['user_type']);
        $query = $pdo->prepare("INSERT INTO accounts (username, email, 
      user_type, password) VALUES(:username,:email,:user_type 
      ,:password)");
        $query->execute(array(':username'       =>$username,
                        ':email'        =>$email,
                        ':user_type'    =>$user_type,
                        ':password'     =>$hashedpwd, ));


        $_SESSION['add']  = "Added successfully";
        header('location: users.php');
        exit(0);
       }else{
        $user_type = 'users';
        $query = $pdo->prepare("INSERT INTO accounts (username, email, 
       user_type, password) VALUES(:username,:email,:user_type 
        ,:password)");
        $query->execute(array(':username'       =>$username,
                        ':email'        =>$email,
                        ':user_type'    =>$user_type,
                        ':password'     =>$hashedpwd, ));



        // get id of the created user
        $logged_in_user_id =  $pdo->lastInsertId();
        $_SESSION['user'] = getUserById($logged_in_user_id); // put logged 
      in user in session
        $_SESSION['add']  = "You are now logged in and thank you!";

        header('location: index.php');
        exit(0);
     }
     }

     }

This is for the login:

        // LOGIN USER
        function login(){
       global $pdo, $errors, $hashedpwd;

      // grab form values
      $email = htmlspecialchars($_POST['email']);
    $password = htmlspecialchars($_POST['password']);

    // make sure form is filled properly
    if (empty($email)) {
    array_push($errors, "Email is required");
    }

    if (empty($password)) {
    array_push($errors, "Password is required");
    }

    // attempt login if no errors on form
     if (count($errors) == 0) {

    $query = $pdo->prepare("SELECT * FROM accounts WHERE email=:email 
    LIMIT 1");
    $query->execute(array(':email'=>$email));
    $row=$query->fetch();

    if ($query->rowCount() > 0) { // check condition database if greater 
      than zero
        $logged_in_user = $query->fetch();

        if ($email==$row['email']) {

            if (password_verify($password, $row['password'])) {

                // check if user is admin or user
                if ($logged_in_user['user_type'] == 'admin') {

                    $_SESSION['user'] = $logged_in_user;
                    $_SESSION['success']  = "You are now logged in";

                    header('location: admin/admin.php');
                    exit(0);
            }else {
                    $_SESSION['user'] = $logged_in_user;
                    $_SESSION['success']  = "You are now logged in";

                    header('location: index.php');
                    exit(0);
            }
        }else{
            array_push($errors, "Wrong password");
        }
    }else {
        array_push($errors, "Wrong username/password combination");
    }
    }
   }
   }