Re: Enabling #define RGB_LED results in compiler error

Good spotting...

Looking just above that error see in Marlin_main.cpp

      #if ENABLED(PRINTER_EVENT_LEDS)
        // Gradually change LED strip from blue to violet as bed heats up
        if (!wants_to_cool) {
          const uint8_t red = map(constrain(temp, start_temp, target_temp), start_temp, target_temp, 0, 255);
          if (red != old_red) set_led_color((old_red = red), 0, 255);
        }
      }
      #endif

the } directly above the # in #endif is in error. Delete that line (line 6921 in the version I have)

ie make it

      #if ENABLED(PRINTER_EVENT_LEDS)
        // Gradually change LED strip from blue to violet as bed heats up
        if (!wants_to_cool) {
          const uint8_t red = map(constrain(temp, start_temp, target_temp), start_temp, target_temp, 0, 255);
          if (red != old_red) set_led_color((old_red = red), 0, 255);
        }
      #endif

I've updated the github issue with these details. One day ill learn how to submit the fix to the real code...