Allow OnUnhandledError to be scoped to modules

[carlganz]

Currently, any callback registered with OnUnhandledError will trigger regardless of where the error occurs or where the callback is registered.

library(shiny)

mod_ui <- function(id) {
  ns <- NS(id)
  uiOutput(ns("sess"))
}

mod_server <- function(input, output, session) {
  onUnhandledError(function(err) {
    # log the unhandled error
    print("inner handler")
  }, session = session)

  output$sess <- renderUI({
# comment this stop out to see how it works when error is outside module
    stop("error msg")
  })
}

# Define UI for application that draws a histogram
ui <- fluidPage(

  mod_ui("test")  ,  uiOutput("sess")
)

# Define server logic required to draw a histogram
server <- function(input, output, session) {
  
  onUnhandledError(function(err) {
    # log the unhandled error
    print("outer handlers")
  }, session = session)
    
callModule(mod_server, "test")
  
output$sess <- renderUI({
 stop("another error msg")
})

}

# Run the application 
shinyApp(ui = ui, server = server)

Regardless of whether the error takes place inside or outside the module both callbacks trigger.

Based on comment here it seems scoping the callbacks to modules would be possible with some updates to session_proxy.

My goal is to use this to create a wrapper of callModule that imitates purrr::safely but reactively so I can call a 3rd party module, and capture an error in the child reactive environment.