fix: Correct backend lint issues

.golangci.yml

@@ -2,7 +2,7 @@ linters-settings:
   dupl:
     threshold: 100
   exhaustive:
-    default-signifies-exhaustive: false
+    default-signifies-exhaustive: true
   funlen:
     lines: 100
     statements: 50

http/data.go

@@ -1,13 +1,14 @@
 package http
 
 import (
+	"errors"
 	"log"
 	"net/http"
 	"strconv"
 
 	"github.com/tomasen/realip"
 
-	"github.com/filebrowser/filebrowser/v2/errors"
+	fbErrors "github.com/filebrowser/filebrowser/v2/errors"
 	"github.com/filebrowser/filebrowser/v2/rules"
 	"github.com/filebrowser/filebrowser/v2/runner"
 	"github.com/filebrowser/filebrowser/v2/settings"
@@ -74,7 +75,8 @@ func handle(fn handleFunc, prefix string, store *storage.Storage, server *settin
 
 		if status != 0 {
 			txt := strconv.Itoa(status) + " " + http.StatusText(status)
-			if httpErr, ok := err.(*errors.HTTPError); ok {
+			var httpErr *fbErrors.HTTPError
+			if errors.As(err, &httpErr) {
 				txt += " [" + httpErr.Type + "]"
 			}
 			http.Error(w, txt, status)

http/resource.go

@@ -670,6 +670,8 @@ func chmodActionHandler(r *http.Request, d *data) error {
 		return fbErrors.ErrInvalidRequestParams
 	}
 
+	permMode := uint32(mode)
+
 	info, err := d.user.Fs.Stat(target)
 	if err != nil {
 		return err
@@ -688,20 +690,20 @@ func chmodActionHandler(r *http.Request, d *data) error {
 				return !i.IsDir()
 			}
 		default:
-			recFilter = func(i os.FileInfo) bool {
+			recFilter = func(_ os.FileInfo) bool {
 				return true
 			}
 		}
 
 		return afero.Walk(d.user.Fs, target, func(name string, info os.FileInfo, err error) error {
 			if err == nil {
 				if recFilter(info) {
-					err = d.user.Fs.Chmod(name, os.FileMode(mode))
+					err = d.user.Fs.Chmod(name, os.FileMode(permMode))
 				}
 			}
 			return err
 		})
 	}
 
-	return d.user.Fs.Chmod(target, os.FileMode(mode))
+	return d.user.Fs.Chmod(target, os.FileMode(permMode))
 }