[Php85] Handle crash on no arg on OrdSingleByteRector (#7682)

* [Php85] Handle crash on no arg on OrdSingleByteRector

* fix

Author: samsonasik

rules-tests/Php85/Rector/FuncCall/OrdSingleByteRector/Fixture/skip_no_arg.php.inc

@@ -0,0 +1,5 @@
+<?php
+namespace Rector\Tests\Php85\Rector\FuncCall\OrdSingleByteRector\Fixture;
+
+echo ord();
+echo "test";

rules/Php85/Rector/FuncCall/OrdSingleByteRector.php

@@ -67,6 +67,10 @@ public function refactor(Node $node): ?Node
         }
 
         $args = $node->getArgs();
+        if (! isset($args[0])) {
+            return null;
+        }
+
         $firstArg = $args[0];
 
         $argExpr = $firstArg->value;