For photo messages, bot will look for commands in the caption if available.

Fixed bug in chatter.lua where the bot will attempt to reply to photo messages.

bot.lua

@@ -37,7 +37,7 @@ end
 
 on_msg_receive = function(msg) -- The fn run whenever a message is received.
 
-	if not msg.text then msg.text = '' end -- So about.lua works.
+	if not msg.text then msg.text = msg.caption or '' end -- So about.lua works.
 	if msg.date < os.time() - 5 then return end -- Do not process old messages.
 
 	msg.chat.id_str = tostring(msg.chat.id)

plugins/chatter.lua

@@ -8,6 +8,8 @@ local triggers = {
 
 local action = function(msg)
 
+	if msg.text == '' then return end
+
 	-- This is awkward, but if you have a better way, please share.
 	if msg.text_lower:match('^' .. bot.first_name .. ',') then
 	elseif msg.text_lower:match('^@' .. bot.username .. ',') then