inc/functions/ip_in_range.php throws error when exploded array lacks 2nd val

I had to modify this

$pieces = explode ("/", $range_ip, 2);
    $left_piece = $pieces[0];
    $right_piece = $pieces[1];

// Extract out the main IP pieces
    $ip_pieces = explode("::", $left_piece, 2);
    $main_ip_piece = $ip_pieces[0];
    $last_ip_piece = $ip_pieces[1];

to something like this

$pieces = explode ("/", $range_ip, 2);
	if (count($pieces) > 0)
    $left_piece = $pieces[0];
	if (count($pieces) > 1)
    $right_piece = $pieces[1];

// Extract out the main IP pieces
    $ip_pieces = explode("::", $left_piece, 2);
	if (count($ip_pieces) > 0)
    $main_ip_piece = $ip_pieces[0];
	if (count($ip_pieces) > 1)
    $last_ip_piece = $ip_pieces[1];

and this
if (trim($last_ip_piece) != "") {

to something like this
if (isset($last_ip_piece) && trim($last_ip_piece) != "") {

in two of the functions.

https://wordpress.org/plugins/w3-total-cache/