Koreader won't start on Kobo without frontlight, powerd.fl may be nil.

reader.lua

@@ -117,6 +117,7 @@ end
 
 -- restore kobo frontlight settings and probe kobo touch coordinates
 if Device:isKobo() then
+    if Device.hasFrontlight then
         local powerd = Device:getPowerDevice()
         if powerd and powerd.restore_settings then
             -- UIManager:init() should have sanely set up the frontlight_stuff by this point
@@ -135,6 +136,7 @@ if Device:isKobo() then
                 powerd.fl:setBrightness(0)
             end
         end
+    end
     if Device:getCodeName() == "trilogy" then
         require("utils/kobo_touch_probe")
     end