The Free On-line Dictionary of Computing (30 December 2018):

light-emitting resistor

    (LER, from "light-emitting diode") A
   resistor in the final stages of burning up.

   (Though intended as purely humorous, the term could sensibly
   describe the filament of a common incandescent electric light
   bulb).

   See also SED.

   (1996-02-06)