no language options on the top right position of the default Shiny app

[jxandy]

The codes and issues are respectively shown as follows:
#1. the codes:

library(shiny)
library(shi18ny)

ui <- fluidPage(
useShi18ny(),
langSelectorInput("lang", position = "fixed"),
h1(ui_("hello")),
uiOutput("results")
)

server <- function(input, output, session) {
i18n <- list(
defaultLang = "en",
availableLangs = c("es","en", "pt")
)
lang <- callModule(langSelector,"lang", i18n = i18n, showSelector = TRUE)
observeEvent(lang(),{
uiLangUpdate(input$shi18ny_ui_classes, lang())
})

output$results <- renderUI({
list(
h1(i_("world",lang())),
br(),
h4(i_("language",lang()), lang())
)
})

}

shinyApp(ui, server)

#2. the issues:
locale directory does not exists, using default translations

Listening on http://127.0.0.1:7753
locale directory does not exists, using default translations
selected2 en config en
TRUE
config_av_langsesenpt
selected3en config en
initLocale: en
input3 is null TRUE
locale directory does not exists, using default translations
locale directory does not exists, using default translations

I would highly appreciate it if you could help me work it out.

Thank you so much in advance!

All the best,
Andy