PHP error message

LoginPress 1.0.2. MAMP 1.9.6. PHP version is 5.3.5.

In my logs, I see the following PHP error message associated with LoginPress:
PHP Warning: call_user_func_array() expects parameter 1 to be a valid callback, class ‘LoginPress’ does not have a method ‘__return_null’ in /Users/username//Sitespath/wp-includes/class-wp-hook.php on line 298

“Username” and “path” are placeholders for my user-specific identity and localhost location.

Is this fixable? Thanks in advance for your input. Great plug-in!