Fix golangci-lint warnings (#17598 et al) (#17668)

Backport #17598 
Backport #17606 
Backport #17608 
Backport #17609

- Since https://gitea.com/gitea/test-env/pulls/10 the golangci-lint has been upgraded and is erroring about new warnings in the code, this PR fixes those warnings.

routers/web/base.go

@@ -130,14 +130,6 @@ func Recovery() func(next http.Handler) http.Handler {
 					log.Error("%v", combinedErr)
 
 					sessionStore := session.GetSession(req)
-					if sessionStore == nil {
-						if setting.IsProd() {
-							http.Error(w, http.StatusText(500), 500)
-						} else {
-							http.Error(w, combinedErr, 500)
-						}
-						return
-					}
 
 					var lc = middleware.Locale(w, req)
 					var store = dataStore{

routers/web/user/setting/adopt.go

@@ -27,7 +27,7 @@ func AdoptOrDeleteRepository(ctx *context.Context) {
 	action := ctx.Query("action")
 
 	ctxUser := ctx.User
-	root := filepath.Join(models.UserPath(ctxUser.LowerName))
+	root := models.UserPath(ctxUser.LowerName)
 
 	// check not a repo
 	has, err := models.IsRepositoryExist(ctxUser, dir)

routers/web/user/setting/profile.go

@@ -246,7 +246,7 @@ func Repos(ctx *context.Context) {
 		repoNames := make([]string, 0, setting.UI.Admin.UserPagingNum)
 		repos := map[string]*models.Repository{}
 		// We're going to iterate by pagesize.
-		root := filepath.Join(models.UserPath(ctxUser.Name))
+		root := models.UserPath(ctxUser.Name)
 		if err := filepath.Walk(root, func(path string, info os.FileInfo, err error) error {
 			if err != nil {
 				if os.IsNotExist(err) {