Merge pull request #14856 from taosdata/fix/tsdbcacheread-close

fix: fix last row reader close memory issues

source/dnode/vnode/src/tsdb/tsdbCacheRead.c

@@ -94,12 +94,15 @@ int32_t tsdbLastRowReaderOpen(void* pVnode, int32_t type, SArray* pTableIdList,
 int32_t tsdbLastrowReaderClose(void* pReader) {
   SLastrowReader* p = pReader;
 
+  if (p->pSchema != NULL) {
     for (int32_t i = 0; i < p->pSchema->numOfCols; ++i) {
       taosMemoryFreeClear(p->transferBuf[i]);
     }
 
-  taosMemoryFree(p->pSchema);
     taosMemoryFree(p->transferBuf);
+    taosMemoryFree(p->pSchema);
+  }
+
   taosMemoryFree(pReader);
   return TSDB_CODE_SUCCESS;
 }