Initialize inline_keyboard array in the constructor

src/TgBotLib/Objects/InlineKeyboardMarkup.php

@@ -12,6 +12,14 @@
          */
         private array $inline_keyboard;
 
+        /**
+         * InlineKeyboardMarkup constructor.
+         */
+        public function __construct()
+        {
+            $this->inline_keyboard = [];
+        }
+
         /**
          * Array of button rows, each represented by an Array of InlineKeyboardButton objects
          *