Fix to solve an issue when hex contains non hexadecimal chars

This fix solve an issue when hex contains non hexadecimal chars, this bug was detected with php 8.0.

Replace the line:

$h = HexDec($hex = strtolower(substr($value, $position+1, 2)));

By the follow two lines:

$hex = strtolower(substr($value, $position+1, 2));
$h = ctype_xdigit($hex) ? HexDec($hex) : -1;

With these lines, the issue will be solved.

Hello Josep,

Thank you again for sharing the fix.

Can you provide an example message that we can use to test the issue?