revert NULL_RANGE usage

Author: soutaro

src/lexstate.c

@@ -94,7 +94,7 @@ static const char *RBS_TOKENTYPE_NAMES[] = {
 
 const rbs_position_t NullPosition = { -1, -1, -1, -1 };
 const rbs_range_t NULL_RANGE = { { -1, -1, -1, -1 }, { -1, -1, -1, -1 } };
-const rbs_token_t NullToken = { .type = NullType, .range = NULL_RANGE };
+const rbs_token_t NullToken = { .type = NullType, .range = {0} };
 
 const char *rbs_token_type_str(enum RBSTokenType type) {
   return RBS_TOKENTYPE_NAMES[type];