fail when trying to encode atom 'undefined'

c_src/encoder.c

@@ -759,6 +759,9 @@ encode_iter(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
                 ret = enc_error(e, "false");
                 goto done;
             }
+        } else if(enif_compare(curr, e->atoms->atom_undefined) == 0) {
+            ret = enc_obj_error(e, "invalid_ejson", curr);
+            goto done;
         } else if(enif_is_binary(env, curr)) {
             if(!enc_string(e, curr)) {
                 ret = enc_obj_error(e, "invalid_string", curr);

c_src/jiffy.c

@@ -34,6 +34,7 @@ load(ErlNifEnv* env, void** priv, ERL_NIF_TERM info)
     st->atom_escape_forward_slashes = make_atom(env, "escape_forward_slashes");
     st->atom_dedupe_keys = make_atom(env, "dedupe_keys");
     st->atom_copy_strings = make_atom(env, "copy_strings");
+    st->atom_undefined = make_atom(env, "undefined");
 
     // Markers used in encoding
     st->ref_object = make_atom(env, "$object_ref$");

c_src/jiffy.h

@@ -37,6 +37,7 @@ typedef struct {
     ERL_NIF_TERM    atom_escape_forward_slashes;
     ERL_NIF_TERM    atom_dedupe_keys;
     ERL_NIF_TERM    atom_copy_strings;
+    ERL_NIF_TERM    atom_undefined;
 
     ERL_NIF_TERM    ref_object;
     ERL_NIF_TERM    ref_array;