Fix errors must not be accessed before initialization

app/Classes/FTN/Process/Ping.php

@@ -50,7 +50,7 @@ final class Ping extends Process
 		$o->tzoffset = $o->datetime->utcOffset();
 
 		$o->reply = $msg->msgid;
-		$o->fftn_id = $ftns->id;
+		$o->fftn_id = $ftns->first()->id;
 		$o->tftn_id = ($x=$msg->fftn_o) ? $x->id : NULL;
 		$o->flags = Message::FLAG_LOCAL;
 		$o->cost = 0;