Merge pull request #19903 from taosdata/fix/TS-2581-2.6

fix(query): fix filterInfo->cunit not allocated caused crash

src/query/src/qFilter.c

@@ -3836,6 +3836,11 @@ _return:
 
 
 int32_t filterGetIndexedColumnInfo(SFilterInfo* info, char** val, int32_t *order, int32_t *flag) {
+  if (FILTER_GET_FLAG(info->status, FI_STATUS_EMPTY)) {
+    *order = 0;
+    return TSDB_CODE_SUCCESS;
+  }
+
   SFilterComUnit *cunit = info->cunits;
   uint8_t optr = cunit->optr;