Fixes for 'equal'

src/utility.c

@@ -177,6 +177,14 @@ struct ucl_object *ucl_progn(struct ucl_scope *state, struct ucl_object *forms)
 
 struct ucl_object *ucl_equal(
     struct ucl_object *arg0, struct ucl_object *arg1) {
+    if (arg0 == arg1) {
+        return ucl_t_create();
+    }
+
+    if ((arg0 == NULL) || (arg1 == NULL)) {
+        return ucl_nil_create();
+    }
+
     if (arg0->type != arg1->type) {
         return ucl_nil_create();
     }