Use the Option type for oldConfigDir variable

themeSwitcher.nim

@@ -1,6 +1,7 @@
 from std/osproc import execProcess, ProcessOption, startProcess, waitForExit, close
 from std/envvars import existsEnv, getEnv, delEnv, putEnv
 from std/os import symlinkExists, getConfigDir, `/`
+from std/options import Option, some, get, isNone
 from std/strutils import split, endsWith
 from std/strformat import fmt
 import owlkettle
@@ -56,16 +57,13 @@ proc setTheme(themeName: string) =
 
 
 var
-  oldConfigDir: string
-  oldConfigDirUnset: bool
+  oldConfigDir: Option[string]
   configDirChanged: bool
 
 # Prevent loading GTK theme from ~/.config/gtk-4.0 directory when it is a symlink
 if symlinkExists(getConfigDir() / "gtk-4.0"):
   if existsEnv("XDG_CONFIG_HOME"):
-    oldConfigDir = getEnv("XDG_CONFIG_HOME")
-  else:
-    oldConfigDirUnset = true
+    oldConfigDir = some(getEnv("XDG_CONFIG_HOME"))
   putEnv("XDG_CONFIG_HOME", "/dev/null")
   configDirChanged = true
 
@@ -76,10 +74,10 @@ viewable App:
     build:
       # Reset the user's XDG_CONFIG_HOME variable back to what it was before
       if configDirChanged == true:
-        if oldConfigDirUnset:
+        if oldConfigDir.isNone():
           delEnv("XDG_CONFIG_HOME")
         else:
-          putEnv("XDG_CONFIG_HOME", oldConfigDir)
+          putEnv("XDG_CONFIG_HOME", get(oldConfigDir))
 
       let currentTheme: string = execProcess("/usr/bin/xfconf-query",
         args=["--channel=xsettings", "--property=/Net/ThemeName"],