don't record error when request a non-exist user (#15819)

* don't record error when request a non-exist user

* Update routers/repo/http.go

Co-authored-by: zeripath <art27@cantab.net>

Co-authored-by: zeripath <art27@cantab.net>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>

routers/repo/http.go

@@ -117,7 +117,7 @@ func httpBase(ctx *context.Context) (h *serviceHandler) {
 			if redirectUserID, err := models.LookupUserRedirect(username); err == nil {
 				context.RedirectToUser(ctx, username, redirectUserID)
 			} else {
-				ctx.NotFound("GetUserByName", err)
+				ctx.NotFound(fmt.Sprintf("User %s does not exist", username), nil)
 			}
 		} else {
 			ctx.ServerError("GetUserByName", err)