fix type conversion warnings in php 8.*

Author: io-developer

src/Iodev/Whois/Modules/Tld/Parsers/BlockParser.php

@@ -425,7 +425,7 @@ protected function parseDate(
             return 0;
         }
         foreach ($sel->getAll() as $str) {
-            if (preg_match($fallbackRegex, $str)) {
+            if ($str && preg_match($fallbackRegex, $str)) {
                 $time = DateHelper::parseDateInText($str);
                 if (!empty($time)) {
                     return $time;

tests/Iodev/Whois/Modules/Tld/TldParsingTest.php

@@ -52,6 +52,9 @@ private static function sort($a)
      */
     private static function parseExpectedDate($datestr)
     {
+        if ($datestr === null) {
+            $datestr = '';
+        }
         // replace %param by value
         if (strpos($datestr, '%') !== false) {
             $datestr = preg_replace('~^%Y(-\d\d-\d\dT\d\d:\d\d)$~', date('Y').'\1', $datestr);