test: attempt to add test for printexn issue

test/print-exn.t

@@ -0,0 +1,26 @@
+An example that uses exceptions runtime
+
+  $ export MELANGELIB="$INSIDE_DUNE/lib/melange"
+  $ mkdir -p node_modules/melange
+  $ ln -s $INSIDE_DUNE/lib node_modules/melange/lib
+
+  $ cat > x.ml <<EOF
+  > let run f =
+  >   try f () with
+  >   | exn -> Printexc.exn_slot_id exn
+  > let result = run (fun _ -> failwith "oops")
+  > EOF
+  $ cat > dune-project <<EOF
+  > (lang dune 3.7)
+  > (using melange 0.1)
+  > EOF
+  $ cat > dune <<EOF
+  > (melange.emit
+  >  (target melange)
+  >  (alias melange)
+  >  (module_system commonjs))
+  > EOF
+  $ dune build @melange
+  $ node ./_build/default/melange/x.js 2>&1 | awk '/exn_slot_id/'
+      return Printexc.exn_slot_id(Caml_js_exceptions.internalToOCamlException(raw_exn));
+  TypeError: Printexc.exn_slot_id is not a function