ScreenSaver: Fix default settings (#7479)

* ScreenSavers: Fix default settings

Awesome typo ;D.

frontend/ui/elements/screensaver_menu.lua

@@ -85,6 +85,7 @@ return {
             return G_reader_settings:isTrue("screensaver_show_message") or G_reader_settings:hasNot("screensaver_type")
         end,
         callback = function()
+            -- NOTE: Since the default is nil, the first toggle will keep it checked (but true instead of nil).
             G_reader_settings:toggle("screensaver_show_message")
         end,
         separator = true,

frontend/ui/screensaver.lua

@@ -24,7 +24,7 @@ local Screen = Device.screen
 local T = require("ffi/util").template
 
 -- Migrate old settings from 2021.02 or older.
-if G_reader_settings:readSetting("screensaver_type", "disable") == "message" then
+if G_reader_settings:readSetting("screensaver_type") == "message" then
     G_reader_settings:saveSetting("screensaver_type", "disable")
     G_reader_settings:makeTrue("screensaver_show_message")
 end