fix(tsdb): add null ptr check.

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

@@ -104,6 +104,10 @@ void *destroyLastBlockLoadInfo(SSttBlockLoadInfo *pLoadInfo) {
 }
 
 void destroySttBlockReader(SLDataIter* pLDataIter, int32_t numOfIter) {
+  if (pLDataIter == NULL) {
+    return;
+  }
+
   for(int32_t i = 0; i < numOfIter; ++i) {
     tLDataIterClose2(&pLDataIter[i]);
   }

source/dnode/vnode/src/tsdb/tsdbRead2.c

@@ -4791,6 +4791,7 @@ static void clearSharedPtr(STsdbReader* p) {
   p->pReadSnap = NULL;
   p->pSchema = NULL;
   p->pSchemaMap = NULL;
+  p->pfSetArray = NULL;
 }
 
 static void setSharedPtr(STsdbReader* pDst, const STsdbReader* pSrc) {
@@ -4800,6 +4801,7 @@ static void setSharedPtr(STsdbReader* pDst, const STsdbReader* pSrc) {
   pDst->pSchema = pSrc->pSchema;
   pDst->pSchemaMap = pSrc->pSchemaMap;
   pDst->pReadSnap = pSrc->pReadSnap;
+  pDst->pfSetArray = pSrc->pfSetArray;
 
   if (pDst->pSchema) {
     tsdbRowMergerInit(&pDst->status.merger, pDst->pSchema);