text: Title: Measurements keep being stored in DB after Input stops working
  Body: hi 
  while it seems that functions and methods do nothing if a sensor stops working it is different with the LCD output. 
  e.g. I have a temp sensor and it shows the temp on the display - if I disconnect the sensor (e.g. if it breaks) the LCD still shows the last fetched temp. (even if this was 10 hours ago) a reboot solves the problem (e.g. I see an error on the display line) 
  
  can I somehow change this (e.g. write to the display no sensor data - if for a period of time no value could be fetched?) - so that I immediately recognize that something is not working? 