FE shutter to display error message on mode setting error

No error message in case of error whent setting mode of FE shutter (ex when doing that during MDT)

SESSION_ID24 [5]: feshut.mode
         Out [5]: 'MANUAL'

SESSION_ID24 [6]: feshut.mode = "AUTOMATIC"
SESSION_ID24 [7]: feshut.mode
         Out [7]: 'MANUAL'