Handle case of area being nil

Author: nickgammon

plugins/ATCP_Mapper.xml

@@ -867,7 +867,7 @@ function get_room (uid)
   end -- for
   table.sort (texits)
    
-  local areaname = room.area
+  local areaname = room.area or "Unknown"
   if tonumber (areaname) then
     areaname = areas [tonumber (areaname)]
   end -- convert to name