What does the error "Notice: Undefined property: JUser::$usertype" in Joomla 3.4 PHP code indicate?

The error "Notice: Undefined property: JUser::$usertype" in Joomla 3.4 PHP code indicates that the property "usertype" is not defined in the JUser class. To solve this issue, you can check if the property exists before trying to access it to avoid the notice. This can be done using the isset() function to check if the property is set in the object.

if(isset($user->usertype)){
    // Property exists, do something with it
    $userType = $user->usertype;
} else {
    // Property does not exist, handle accordingly
    $userType = 'default';
}