TD-6129<feature> support null true false for json tag

src/client/src/tscUtil.c

@@ -5269,7 +5269,7 @@ char* parseTagDatatoJson(void *p){
       char type = *(char*)val;
       if(type == TSDB_DATA_TYPE_NCHAR) {
         int32_t length = taosUcs4ToMbs(varDataVal(realData), varDataLen(realData), tagJsonValue);
-        if (length == 0) {
+        if (length < 0) {
           tscError("charset:%s to %s. val:%s convert json value failed.", DEFAULT_UNICODE_ENCODEC, tsCharset,
                    (char*)val);
           goto end;

tests/pytest/stable/json_tag.py

@@ -168,7 +168,7 @@ class TDTestCase:
 
         # test json
         tdSql.error("CREATE TABLE if not exists db_json_tag_test.jsons1_5 using db_json_tag_test.jsons1 tags('efwewf')")
-        tdSql.execute("CREATE TABLE if not exists db_json_tag_test.jsons1_5 using db_json_tag_test.jsons1 tags('\t')")
+        tdSql.error("CREATE TABLE if not exists db_json_tag_test.jsons1_5 using db_json_tag_test.jsons1 tags('\t')")
         tdSql.execute("CREATE TABLE if not exists db_json_tag_test.jsons1_6 using db_json_tag_test.jsons1 tags('')")
         tdSql.execute("CREATE TABLE if not exists db_json_tag_test.jsons1_7 using db_json_tag_test.jsons1 tags('{}')")
         tdSql.execute("CREATE TABLE if not exists db_json_tag_test.jsons1_8 using db_json_tag_test.jsons1 tags('null')")