Common PHP and WordPress errors and how to fix them

Solution:

Without knowing exactly what the function was doing, it’s hard to provide a precise fix. However, to clear the error, you can define the function in your functions.php file like this (as you’ve already attempted):

function custom_modify_title($args = array()) {
    return $args;
}

After that, you can work on restoring the lost functionality by checking the plugin documentation here:
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