getChatMember - mkotb/Telegram-Errors GitHub Wiki

If not provided, Telegram will return chat_id is empty.

If the bot doesn't have access to the chat, or it doesn't exist, Telegram will return chat not found.

if not provided, Telegram will return wrong user_id specified.

If an invalid user id is provided, a ChatMember object will be returned, however, it will not display their name and they will be shown as left.