refactor(consts): lazily initialize cache dir

internal/consts/consts.go

@@ -4,25 +4,26 @@ import (
 	"log/slog"
 	"os"
 	"path/filepath"
+	"sync"
 )
 
 const Name = "discordo"
 
-var cacheDir string
-
-func CacheDir() string {
-	return cacheDir
-}
-
-func init() {
+var cacheDir = sync.OnceValue(func() string {
 	userCacheDir, err := os.UserCacheDir()
 	if err != nil {
 		userCacheDir = os.TempDir()
 		slog.Warn("failed to get user cache dir; falling back to temp dir", "err", err, "path", userCacheDir)
 	}
 
-	cacheDir = filepath.Join(userCacheDir, Name)
-	if err := os.MkdirAll(cacheDir, os.ModePerm); err != nil {
-		slog.Error("failed to create cache dir", "err", err, "path", cacheDir)
+	path := filepath.Join(userCacheDir, Name)
+	if err := os.MkdirAll(path, os.ModePerm); err != nil {
+		slog.Error("failed to create cache dir", "err", err, "path", path)
 	}
+
+	return path
+})
+
+func CacheDir() string {
+	return cacheDir()
 }