js_of_ocaml custom directory

README.md

dune build main.bc.js --release
node _build/default/main.bc.js

Returns

$node _build/default/main.bc.js
/home/philip/Documents/ocaml/bapjs2/jsoo_crash/_build/default/main.bc.js:3937
       {r += exn[1][1];
                   ^

TypeError: Cannot read property '1' of undefined
    at caml_format_exception (/home/philip/Documents/ocaml/bapjs2/jsoo_crash/_build/default/main.bc.js:3937:20)
    at caml_fatal_uncaught_exception (/home/philip/Documents/ocaml/bapjs2/jsoo_crash/_build/default/main.bc.js:3976:16)
    at process.<anonymous> (/home/philip/Documents/ocaml/bapjs2/jsoo_crash/_build/default/main.bc.js:5753:12)
    at process.emit (events.js:314:20)
    at process._fatalException (internal/process/execution.js:165:25)

dune

(executable
 (name main)
 (modes byte js)
 (js_of_ocaml (flags  --pretty
 --file /home/philip/Documents/ocaml/bapjs2/jsoo_crash/mytest.txt:/custom-folder/
 ))
)

main.ml

let () = Array.iter (fun d -> print_endline d) (Sys.readdir "/static/")

mytest.txt

Hello world