fix(evm): make conditional balance check free in gas cost (#2114)

* fix(evm): make conditional balance check free in gas cost

* chore: update changelog

CHANGELOG.md

@@ -106,6 +106,7 @@ feat(evm-funtoken-precompile): Implement methods: balance, bankBalance, whoAmI
 - [#2108](https://github.com/NibiruChain/nibiru/pull/2108) - fix(evm): removed deprecated root key from eth_getTransactionReceipt
 - [#2110](https://github.com/NibiruChain/nibiru/pull/2110) - fix(evm): Restore StateDB to its state prior to ApplyEvmMsg call to ensure deterministic gas usage. This fixes an issue where the StateDB pointer field in NibiruBankKeeper was being updated during readonly query endpoints like eth_estimateGas, leading to non-deterministic gas usage in subsequent transactions.
 - [#2111](https://github.com/NibiruChain/nibiru/pull/2111) - fix: e2e-evm-cron.yml
+- [#2114](https://github.com/NibiruChain/nibiru/pull/2114) - fix(evm): make gas cost zero in conditional bank keeper flow
 
 #### Nibiru EVM | Before Audit 1 - 2024-10-18
 

x/evm/keeper/bank_extension.go

@@ -1,6 +1,7 @@
 package keeper
 
 import (
+	storetypes "github.com/cosmos/cosmos-sdk/store/types"
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	auth "github.com/cosmos/cosmos-sdk/x/auth/types"
 	bankkeeper "github.com/cosmos/cosmos-sdk/x/bank/keeper"
@@ -84,6 +85,14 @@ func (bk *NibiruBankKeeper) SyncStateDBWithAccount(
 	if bk.StateDB == nil {
 		return
 	}
+
+	cachedGasConfig := ctx.KVGasConfig()
+	defer func() {
+		ctx = ctx.WithKVGasConfig(cachedGasConfig)
+	}()
+
+	// set gas cost to zero for this conditional operation
+	ctx = ctx.WithKVGasConfig(storetypes.GasConfig{})
 	balanceWei := evm.NativeToWei(
 		bk.GetBalance(ctx, acc, evm.EVMBankDenom).Amount.BigInt(),
 	)