From 4893faa374655e749d378b0350238a823af88493 Mon Sep 17 00:00:00 2001
From: Anna Shaleva <shaleva.ann@nspcc.ru>
Date: Fri, 12 Feb 2021 23:23:24 +0300
Subject: [PATCH] core: remove NEP17BalanceState if balance is null [addTokens]

Affects states.
---
 pkg/core/native/native_nep17.go | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/pkg/core/native/native_nep17.go b/pkg/core/native/native_nep17.go
index 7c2a0f1c7..359f65f25 100644
--- a/pkg/core/native/native_nep17.go
+++ b/pkg/core/native/native_nep17.go
@@ -258,13 +258,19 @@ func (c *nep17TokenNative) addTokens(ic *interop.Context, h util.Uint160, amount
 	if err := c.incBalance(ic, h, si, amount); err != nil {
 		panic(err)
 	}
-	if err := ic.DAO.PutStorageItem(c.ID, key, si); err != nil {
+	var err error
+	if si.Value == nil {
+		err = ic.DAO.DeleteStorageItem(c.ID, key)
+	} else {
+		err = ic.DAO.PutStorageItem(c.ID, key, si)
+	}
+	if err != nil {
 		panic(err)
 	}
 
 	supply := c.getTotalSupply(ic.DAO)
 	supply.Add(supply, amount)
-	err := c.saveTotalSupply(ic.DAO, supply)
+	err = c.saveTotalSupply(ic.DAO, supply)
 	if err != nil {
 		panic(err)
 	}