pr_set_error() doesn't apply to endpoints defined inside pr_mount()

[gacolitti]

I expect pr_set_error() to be invoked when hitting endpoints defined inside pr_mount():

library(plumber)

pr1 <- pr() |> 
  pr_get("/error", function() log("a"))  

pr() |>
  pr_mount("/get", pr1) |>
  pr_set_error(function(req, res, err) {
    browser()
  }) |>
  pr_run()

In this example, the handler function inside pr_set_error() is never invoked when hitting the /get/error endpoint.

[thomasp85]

This is because the default error handler of pr1 catches the error so that it never bubbles up to the parent pr

If you want the the behaviour you are after you can turn off the error handling in pr1

library(plumber)

pr1 <- pr() |> 
  pr_get("/error", function() log("a"))  |>
  pr_set_error(NULL)

pr() |>
  pr_mount("/get", pr1) |>
  pr_set_error(function(req, res, err) {
    browser()
  }) |>
  pr_run()