Merge pull request #20403 from taosdata/fix/main_wxy

fix: invalid topic query

source/libs/parser/src/parTranslater.c

@@ -5573,7 +5573,8 @@ static int32_t checkCreateTopic(STranslateContext* pCxt, SCreateTopicStmt* pStmt
 
   if (QUERY_NODE_SELECT_STMT == nodeType(pStmt->pQuery)) {
     SSelectStmt* pSelect = (SSelectStmt*)pStmt->pQuery;
-    if (!pSelect->isDistinct && QUERY_NODE_REAL_TABLE == nodeType(pSelect->pFromTable) &&
+    if (!pSelect->isDistinct &&
+        (NULL != pSelect->pFromTable && QUERY_NODE_REAL_TABLE == nodeType(pSelect->pFromTable)) &&
         NULL == pSelect->pGroupByList && NULL == pSelect->pLimit && NULL == pSelect->pSlimit &&
         NULL == pSelect->pOrderByList && NULL == pSelect->pPartitionByList) {
       return TSDB_CODE_SUCCESS;