Ensure return type is always array

Author: nicolaasuni

include/tcpdf_static.php

@@ -1776,7 +1776,11 @@ public static function pregSplit($pattern, $modifiers, $subject, $limit=NULL, $f
 		$flags = $flags === null ? 0 : $flags;
 		// the bug only happens on PHP 5.2 when using the u modifier
 		if ((strpos($modifiers, 'u') === FALSE) OR (count(preg_split('//u', "\n\t", -1, PREG_SPLIT_NO_EMPTY)) == 2)) {
-			return preg_split($pattern.$modifiers, $subject, $limit, $flags);
+			$ret = preg_split($pattern.$modifiers, $subject, $limit, $flags);
+			if $ret === false {
+				return array();
+			}
+			return $ret;
 		}
 		// preg_split is bugged - try alternative solution
 		$ret = array();