ante: fix panic in when gas price larger than 100000 (#750)

CHANGELOG.md

@@ -43,7 +43,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 * (evm) [\#670](https://github.com/cosmos/ethermint/pull/670) Migrate types to the ones defined by the protobuf messages, which are required for the stargate release.
 
 ### Bug Fixes
-
+* (evm) [\#749](https://github.com/cosmos/ethermint/issues/749) Fix panic in `AnteHandler` when gas price larger than 100000
 * (evm) [\#747](https://github.com/cosmos/ethermint/issues/747) Fix format errors in String() of QueryETHLogs
 * (evm) [\#742](https://github.com/cosmos/ethermint/issues/742) Add parameter check for evm query func. 
 * (evm) [\#687](https://github.com/cosmos/ethermint/issues/687) Fix nonce check to explicitly check for the correct nonce, rather than a simple 'greater than' comparison. 

app/ante/eth.go

@@ -101,7 +101,7 @@ func (emfd EthMempoolFeeDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx, simula
 	evmDenom := emfd.evmKeeper.GetParams(ctx).EvmDenom
 
 	// fee = gas price * gas limit
-	fee := sdk.NewInt64DecCoin(evmDenom, msgEthTx.Fee().Int64())
+	fee := sdk.NewDecCoin(evmDenom, sdk.NewIntFromBigInt(msgEthTx.Fee()))
 
 	minGasPrices := ctx.MinGasPrices()
 	minFees := minGasPrices.AmountOf(evmDenom).MulInt64(int64(msgEthTx.Data.GasLimit))