Mixing chinese and arabic characters in the safe HTML node blocks PDF generation

[SpyroTEQ]

(I will report this in the new library, because I cannot open issues on the deprecated old one)

When mixing some RTL characters with some other UTF8 characters in the same HTML node, like when mixing Chinese characters and Arabic characters (嫀 ط), then TCPDF screams a notice and the PDF is not built.

This happens on latest 6.2 version of TCPDF (and on elder ones like 5.9), using PHP 5.6.25

Showcase:

set_include_path(get_include_path() . PATH_SEPARATOR . __DIR__);
spl_autoload_register();
error_reporting(E_ALL);

$pdf = new TCPDF('P', 'mm', 'A4');

// This one works
//$string = "<span>&#23232;</span> <span>&#1591;</span>";
//
// This one fails
$string = "&#23232; &#1591;";

echo($string);
var_dump($string);

$pdf->AddPage();
$pdf->writeHTML($string);
$pdfContent = $pdf->Output('doc.pdf', 'S');
// Screams ( ! ) Notice: Undefined offset: 23232 in C:\wamp\www\TCPDF-master\include\tcpdf_fonts.php on line 2119

var_dump($pdfContent);

Result:
嫀 ط
C:\wamp\www\TCPDF-master\test-8576.php:16:string '嫀 ط' (length=16)

( ! ) Notice: Undefined offset: 23232 in C:\wamp\www\TCPDF-master\include\tcpdf_fonts.php on line 2119

And the PDF is not generated.

[nicolaasuni]

This message is for another library.
This is the new version.