fix: add burn method when coin is made from evm side

x/evm/precompile/funtoken.go

@@ -573,6 +573,14 @@ func (p precompileFunToken) sendToEvm(
 		return nil, fmt.Errorf("failed to send coins to module: %w", err)
 	}
 
+	// burn if funtoken was created from EVM side
+	if !funtoken.IsMadeFromCoin {
+		err := p.evmKeeper.Bank.BurnCoins(ctx, evm.ModuleName, sdk.NewCoins(coinToSend))
+		if err != nil {
+			return nil, fmt.Errorf("failed to burn coins: %w", err)
+		}
+	}
+
 	// 2) mint (or unescrow) the ERC20
 	erc20Addr := funtoken.Erc20Addr.Address
 	actualAmt, err := p.mintOrUnescrowERC20(

x/evm/precompile/funtoken_test.go

@@ -485,6 +485,11 @@ func (s *FuntokenSuite) TestSendToEvm() {
 	bankBal := deps.App.BankKeeper.GetBalance(deps.Ctx, deps.Sender.NibiruAddr, bankDenom).Amount.BigInt()
 	s.EqualValues(wantBank, bankBal, "did user lose 1000 unibi from bank?")
 
+	// check the evm module account balance
+	wantEvm := big.NewInt(1000)
+	evmBal := deps.App.BankKeeper.GetBalance(deps.Ctx, evm.EVM_MODULE_ADDRESS[:], bankDenom).Amount.BigInt()
+	s.EqualValues(wantEvm, evmBal, "did evm module gain 1000 unibi?")
+
 	s.T().Log("Check the user gained 1000 in ERC20 representation")
 	evmtest.AssertERC20BalanceEqual(s.T(), deps, erc20Addr, deps.Sender.EthAddr, big.NewInt(1000))
 }
@@ -559,7 +564,7 @@ func (s *FuntokenSuite) TestBankMsgSend() {
 }
 
 func bigTokens(n int64) *big.Int {
-	e18 := big.NewInt(1_000_000_000_000_000_000) // 1e18
+	e18 := big.NewInt(1e18) // 1e18
 	return new(big.Int).Mul(big.NewInt(n), e18)
 }
 
@@ -648,6 +653,13 @@ func (s *FuntokenSuite) TestSendToEvm_NotMadeFromCoin() {
 	balAfter := deps.App.BankKeeper.GetBalance(deps.Ctx, alice.NibiruAddr, bankBal.Denom).Amount.BigInt()
 	s.Require().EqualValues(bigTokens(0), balAfter)
 
+	// check bob has 500 tokens again => 500 * 1e18
+	evmtest.AssertERC20BalanceEqual(s.T(), deps, erc20Addr, bob.EthAddr, bigTokens(500))
+
+	// check evm module account's balance
+	evmBal := deps.App.BankKeeper.GetBalance(deps.Ctx, evm.EVM_MODULE_ADDRESS[:], bankBal.Denom).Amount.BigInt()
+	s.Require().EqualValues(bigTokens(0), evmBal)
+
 	// user has 500 tokens again => 500 * 1e18
 	evmtest.AssertERC20BalanceEqual(s.T(), deps, erc20Addr, bob.EthAddr, bigTokens(500))
 }