fix(virtual_lib_compilation_test): only add dependency if impl exists

Signed-off-by: Antonio Nuno Monteiro <anmonteiro@gmail.com>

src/dune_rules/melange/melange_rules.ml

@@ -219,8 +219,14 @@ let build_js
             let+ module_deps =
               Dep_rules.immediate_deps_of m modules ~obj_dir ~ml_kind:Impl
             in
-            List.map module_deps ~f:(fun dep_m ->
-              Obj_dir.Module.cm_file_exn obj_dir dep_m ~kind:(Melange Cmj) |> Path.build)
+            List.fold_left module_deps ~init:[] ~f:(fun acc dep_m ->
+              if Module.has dep_m ~ml_kind:Impl
+              then (
+                let cmj_file =
+                  Obj_dir.Module.cm_file_exn obj_dir dep_m ~kind:(Melange Cmj)
+                in
+                Path.build cmj_file :: acc)
+              else acc)
           | None -> Action_builder.return []
         in
         Action_builder.dyn_paths_unit local_library_paths >>> command)