Improve error messages about wrapper segments from Message::parse()

Author: Philipp91

lib/Fhp/Protocol/Message.php

@@ -300,14 +300,16 @@ public static function parse(string $rawMessage): Message
         $segments = Parser::parseSegments($rawMessage);
 
         // Message header and footer must always be there, or something went badly wrong.
-        if (!($segments[0] instanceof HNHBKv3)) {
-            throw new \InvalidArgumentException("Expected first segment to be HNHBK: $rawMessage");
-        }
-        if (!($segments[count($segments) - 1] instanceof HNHBSv1)) {
-            throw new \InvalidArgumentException("Expected last segment to be HNHBS: $rawMessage");
-        }
         $result->header = $segments[0];
         $result->footer = $segments[count($segments) - 1];
+        if (!($result->header instanceof HNHBKv3)) {
+            $actual = $result->header->getName();
+            throw new \InvalidArgumentException("Expected first segment to be HNHBK, but got $actual: $rawMessage");
+        }
+        if (!($result->footer instanceof HNHBSv1)) {
+            $actual = $result->footer->getName();
+            throw new \InvalidArgumentException("Expected last segment to be HNHBS, but got $actual: $rawMessage");
+        }
 
         // Check if there's an encryption header and "encrypted" data.
         // Section B.8 specifies that there are exactly 4 segments: HNHBK, HNVSK, HNVSD, HNHBS.