Fixed PluginCommand usage messages

Author: dktapps

src/plugin/PluginBase.php

@@ -163,7 +163,7 @@ private function registerYamlCommands() : void{
 				$this,
 				$this,
 				$data->getDescription() ?? "",
-				$data->getUsageMessage() ?? ""
+				$data->getUsageMessage()
 			);
 
 			$newCmd->setPermission($data->getPermission());