compilation fails when `~/.config/dune` is a regular file

Expected Behavior

opam install dune should work

Actual Behavior

<><> Processing actions <><><><><><><><><><><><><><><><><><><><><><><><><><><><>
⬇ retrieved dune.3.24.0  (https://opam.ocaml.org/cache)
[ERROR] The compilation of dune.3.24.0 failed at "./_boot/dune.exe build dune.install --release --profile dune-bootstrap -j 255".

#=== ERROR while compiling dune.3.24.0 ========================================#
# context     2.5.0 | linux/x86_64 |  | [https://opam.ocaml.org#5a33333c8870d0aaddae16eba9590b79f871a90c](https://opam.ocaml.org/#5a33333c8870d0aaddae16eba9590b79f871a90c)
# path        ~/work/monorepo/_opam/.opam-switch/build/dune.3.24.0
# command     ~/.opam/opam-init/hooks/sandbox.sh build ./_boot/dune.exe build dune.install --release --profile dune-bootstrap -j 255
# exit-code   2
# env-file    ~/.opam/log/dune-2031856-ef3205.env
# output-file ~/.opam/log/dune-2031856-ef3205.out
### output ###
# dune: internal error, uncaught exception:
# [...]
#       Called from Cmdliner_term.app.(fun) in file "cmdliner_term.ml", line 22, characters 12-19
#       Called from Cmdliner_term.app.(fun) in file "cmdliner_term.ml", line 19, characters 21-30
#       Called from Cmdliner_term.app.(fun) in file "cmdliner_term.ml", line 22, characters 12-19
#       Called from Cmdliner_term.app.(fun) in file "cmdliner_term.ml", line 19, characters 21-30
#       Called from Cmdliner_term.app.(fun) in file "cmdliner_term.ml", line 22, characters 12-19
#       Called from Cmdliner_term.app.(fun) in file "cmdliner_term.ml", line 19, characters 21-30
#       Called from Cmdliner_term.app.(fun) in file "cmdliner_term.ml", line 22, characters 12-19
#       Called from Cmdliner_eval.run_parser in file "cmdliner_eval.ml", line 34, characters 37-44
# Fatal error: exception ("Unexpected result evaluating term with no args", { error = "exn" })
# Raised at Stdune__Code_error.raise in file "stdune__Code_error.ml", line 11, characters 30-62
# Called from Dune_exe__Common.Builder.default in file "dune_exe__Common.ml", line 1005, characters 16-48



<><> Error report <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
┌─ The following actions failed
│ λ build dune 3.24.0
└─
╶─ No changes have been performed

Reproduction

1. touch ~/.config/dune
2. opam install dune.3.24.0

Specifications

• Version of dune (output of dune --version): 3.24.0
• Operating system (distribution and version): debian bookworm

Additional information

I think the issue is Std.Fpath.exists, it catches ENOENT but it should also catch ENOTDIR and maybe a bunch of others too.