new_contents: # -*- coding: utf-8 -*-
  import PIL.Image
  
  # check for JPEG support.
  try:
      PIL.Image._getdecoder("rgb", "jpeg", None)
  except IOError as e:
      if str(e).startswith("decoder jpeg not available"):
          raise Exception(
              "FATAL: jpeg codec not supported. Install pillow correctly! "
              " 'sudo apt-get install libjpeg-dev' then 'pip install -I pillow'"
          )
  except Exception:
      # any other exception is fine
      pass
  
  
  # check for PNG support.
  try:
      PIL.Image._getdecoder("rgb", "zip", None)
  except IOError as e:
      if str(e).startswith("decoder zip not available"):
          raise Exception(
              "FATAL: zip codec not supported. Install pillow correctly! "
              " 'sudo apt-get install libjpeg-dev' then 'pip install -I pillow'"
          )
  except Exception:
      # any other exception is fine
      pass
subject: Add runtime checks on startup to enforce that JPEG/PNG support is included when installing pillow.