load_photo crash when loading from old forwarded bot message

[3bl3gamer]

Looks like bots clean up their messages after a month or two. If forwarded to a dialog, such message will remain in dialog, but as soon as original bot message is removed, official client will show comething like this:

get_message <id> on that message returns this:

{
  "id": "010000005c80fc03a31b0100000000004510d8a58edc3a47",
  "from": {...},
  "to": {...},
  "event": "message",
  "fwd_from": {"id": "$01000000a4f73b022fcdf4eec56f06b8", "peer_type": "user", "peer_id": 37484452, "print_name": "ImageSearch", "flags": 1, "last_name": "", "first_name": "ImageSearch", "username": "ImageSearchBot"},
  "fwd_date": 1450656733,
  "flags": 256,
  "out": false,
  "media": {"caption": "", "type": "photo"},
  "unread": false,
  "service": false,
  "date": 1450656738
}

but load_image <id> will crash telegram-cli: message is "media_photo" but has no photo, so here https://github.com/vysheng/tg/blob/master/interface.c#L1485 M->media.photo is NULL:

if (M->media.type == tgl_message_media_photo) { \
  tgl_do_load_photo (TLS, M->media.photo, actf, ev);\
} else

and then here https://github.com/vysheng/tgl/blob/master/queries.c#L3304 tgl_do_load_photo crashes because of null pointer.

[blaize9]

@3bl3gamer I have submitted a pull request vysheng/tgl/pull#106 which would fix this issue.