Add fixed overhead to callGasLimit estimate (#146)

Author: hazim-j

pkg/gas/callgas.go

@@ -42,11 +42,12 @@ func CallGasEstimate(
 		return 0, err
 	}
 
+	ov := NewDefaultOverhead()
 	tg := big.NewInt(0).Div(sim.Paid, op.MaxFeePerGas)
-	cgl := big.NewInt(0).Sub(tg, sim.PreOpGas)
-	call := NewDefaultOverhead().NonZeroValueCall()
-	if cgl.Cmp(call) >= 1 {
+	cgl := big.NewInt(0).Add(big.NewInt(0).Sub(tg, sim.PreOpGas), big.NewInt(int64(ov.fixed)))
+	min := ov.NonZeroValueCall()
+	if cgl.Cmp(min) >= 1 {
 		return cgl.Uint64(), nil
 	}
-	return call.Uint64(), nil
+	return min.Uint64(), nil
 }

pkg/gas/overhead.go

@@ -44,7 +44,7 @@ func (ov *Overhead) CalcPreVerificationGas(op *userop.UserOperation) *big.Int {
 // See https://github.com/wolflo/evm-opcodes/blob/main/gas.md#aa-1-call.
 func (ov *Overhead) NonZeroValueCall() *big.Int {
 	return big.NewInt(
-		int64(ov.warmStorageRead + ov.nonZeroValueCall + ov.callOpcode + ov.nonZeroValueStipend),
+		int64(ov.fixed + ov.warmStorageRead + ov.nonZeroValueCall + ov.callOpcode + ov.nonZeroValueStipend),
 	)
 }