Directly translate images only on private chats

@@ -272,10 +272,16 @@ bot.onText(/^\/(t|translate)($| ((.|\n)+))/, (msg, match) => {
 bot.on('photo', (msg) => {
   const user = msg.from;
   const chatId = msg.chat.id;
+  const chatType = msg.chat.type;
   const photo = msg.photo[msg.photo.length - 1]; // Choose largest image possible
   const photoId = photo.file_id;
   const caption = msg.caption;
 
+  // Ignore if we are not on a private chat
+  if (chatType != 'private') {
+    return;
+  }
+
   // Detect text from given image
   detectText(photoId).then(function (text) {
     // Translate the result