Control unknown messages

[manzanit0]

Certain interactions, specially in Telegram, send messages with different payloads, for example when interacting with an inlined button, or when sending an image. It would be convenient to adapt the webhook endpoint to simply ignore those and notify the user to not send such messages.

I noticed that button callbacks cause a crash. This was noticed when sending and interacting with the following message:

{
  "chat_id": *****,
	"text": "These are your current subscriptions. Feel free to subscribe or unsubscribe to the lines of your choice!",
	"parse_mode": "markdown",
	"reply_markup": {
		"keyboard":  [
			[
				{
					"text": "Bakerloo ✔️",
					"callback_data": "A1"            
				},
				{
					"text": "Central",
					"callback_data": "A1"            
				}, 
				{
					"text": "Circle",
					"callback_data": "A1"            
				}
			],
			[
				{
					"text": "District",
					"callback_data": "C1"            
				},
				{
					"text": "DLR",
					"callback_data": "A1"            
				},
				{
					"text": "Hammesmith",
					"callback_data": "C1"            
				}],
			[
				{
					"text": "Jubilee",
					"callback_data": "C1"            
				},
				{
					"text": "Overground",
					"callback_data": "C1"            
				},
				{
					"text": "Metropolitan",
					"callback_data": "A1"            
				}],
			[
				{
					"text": "Northern",
					"callback_data": "A1"            
				},
				{
					"text": "Picadilly",
					"callback_data": "A1"            
				},
				{
					"text": "TFL Rail",
					"callback_data": "A1"            
				}
			],
			[
				{
					"text": "Victoria ✔️",
					"callback_data": "A1"            
				},
				{
					"text": "Waterloo",
					"callback_data": "A1"            
				}]
		]}
}