Update blockchain.go

receipts may be null for very short time in some condition. For this case, we should not add the null value into cache. Because you will not get the right result if you keep requesting that receipt.

core/blockchain.go

@@ -644,6 +644,9 @@ func (bc *BlockChain) GetReceiptsByHash(hash common.Hash) types.Receipts {
 		return nil
 	}
 	receipts := rawdb.ReadReceipts(bc.db, hash, *number)
+	if receipts == nil {
+		return nil
+	}
 	bc.receiptsCache.Add(hash, receipts)
 	return receipts
 }