Fix Trying to access array offset on value of type null

Author: remicollet

test/HTML5/Parser/TokenizerTest.php

@@ -26,7 +26,8 @@ public function assertEventEquals($type, $expects, $event)
         if (is_array($expects)) {
             $this->assertEquals($expects, $event['data'], "Event $type should equal " . print_r($expects, true) . ': ' . print_r($event, true));
         } else {
-            $this->assertEquals($expects, $event['data'][0], "Event $type should equal $expects: " . print_r($event, true));
+            $d = (is_array($event['data']) ? $event['data'][0] : null);
+            $this->assertEquals($expects, $d, "Event $type should equal $expects: " . print_r($event, true));
         }
     }