diff --git a/src/endstone_test/event_listener.py b/src/endstone_test/event_listener.py
index 51f5bd3..2bc5d2e 100644
--- a/src/endstone_test/event_listener.py
+++ b/src/endstone_test/event_listener.py
@@ -78,11 +78,12 @@ def send_welcome_message(player_name: str) -> None:
 
         skin = event.player.skin
         self._plugin.logger.info(f"Skin Id: {skin.skin_id}, Cape Id: {skin.cape_id}")
-        assert skin.skin_data.shape[2] == 4
+        assert skin.skin_data.shape[2] == 4, f"Bad shape for skin data: {skin.skin_data.shape}"
         skin_path = Path(self._plugin.data_folder) / "skins"
         skin_path.mkdir(parents=True, exist_ok=True)
         Image.fromarray(skin.skin_data).save(skin_path / f"{event.player.name}.png")
         if skin.cape_data is not None:
+            assert skin.cape_data.shape[2] == 4, f"Bad shape for cape data: {skin.cape_data.shape}"
             Image.fromarray(skin.cape_data).save(skin_path / f"{event.player.name}_cape.png")
 
     @event_handler
diff --git a/src/endstone_test/plugin.py b/src/endstone_test/plugin.py
index db94c28..56d298e 100644
--- a/src/endstone_test/plugin.py
+++ b/src/endstone_test/plugin.py
@@ -1,7 +1,8 @@
 import datetime
 import uuid
 
-from endstone import __minecraft_version__
+from endstone import __minecraft_version__, Player
+from endstone.command import Command, CommandSender, ConsoleCommandSender
 from endstone.plugin import Plugin
 
 from endstone_test.event_listener import EventListener
@@ -62,6 +63,15 @@ def on_enable(self) -> None:
     def on_disable(self) -> None:
         self.logger.info("on_disable is called!")
 
+    def on_command(self, sender: CommandSender, command: Command, args: list[str]) -> bool:
+        if isinstance(sender, ConsoleCommandSender):
+            sender.send_message("You are the console!")
+        elif isinstance(sender, Player):
+            sender.send_message("You are the player!")
+        else:
+            sender.send_message(f"You are {sender.__class__}!")
+        return True
+
     def send_debug_message(self):
         for player in self.server.online_players:
             player.send_tip(