chore: fix golangci-lint errors

http/auth.go

@@ -2,6 +2,7 @@ package http
 
 import (
 	"encoding/json"
+	"errors"
 	"log"
 	"net/http"
 	"os"
@@ -11,7 +12,7 @@ import (
 	"github.com/golang-jwt/jwt/v4"
 	"github.com/golang-jwt/jwt/v4/request"
 
-	"github.com/filebrowser/filebrowser/v2/errors"
+	fbErrors "github.com/filebrowser/filebrowser/v2/errors"
 	"github.com/filebrowser/filebrowser/v2/users"
 )
 
@@ -65,7 +66,7 @@ func (e extractor) ExtractToken(r *http.Request) (string, error) {
 
 func withUser(fn handleFunc) handleFunc {
 	return func(w http.ResponseWriter, r *http.Request, d *data) (int, error) {
-		keyFunc := func(token *jwt.Token) (interface{}, error) {
+		keyFunc := func(_ *jwt.Token) (interface{}, error) {
 			return d.settings.Key, nil
 		}
 
@@ -109,13 +110,14 @@ func loginHandler(tokenExpireTime time.Duration) handleFunc {
 		}
 
 		user, err := auther.Auth(r, d.store.Users, d.settings, d.server)
-		if err == os.ErrPermission {
+		switch {
+		case errors.Is(err, os.ErrPermission):
 			return http.StatusForbidden, nil
-		} else if err != nil {
+		case err != nil:
 			return http.StatusInternalServerError, err
-		} else {
-			return printToken(w, r, d, user, tokenExpireTime)
 		}
+
+		return printToken(w, r, d, user, tokenExpireTime)
 	}
 }
 
@@ -124,7 +126,7 @@ type signupBody struct {
 	Password string `json:"password"`
 }
 
-var signupHandler = func(w http.ResponseWriter, r *http.Request, d *data) (int, error) {
+var signupHandler = func(_ http.ResponseWriter, r *http.Request, d *data) (int, error) {
 	if !d.settings.Signup {
 		return http.StatusMethodNotAllowed, nil
 	}
@@ -165,7 +167,7 @@ var signupHandler = func(w http.ResponseWriter, r *http.Request, d *data) (int,
 	log.Printf("new user: %s, home dir: [%s].", user.Username, userHome)
 
 	err = d.store.Users.Save(user)
-	if err == errors.ErrExist {
+	if errors.Is(err, fbErrors.ErrExist) {
 		return http.StatusConflict, err
 	} else if err != nil {
 		return http.StatusInternalServerError, err