core: handle ignored error

- according to implementation of `IntrinsicGas`
we can continue execution since problem will be detected
later. However, early return is future-proof for changes.

core/state_transition.go

@@ -215,6 +215,9 @@ func (st *StateTransition) TransitionDb() (ret []byte, usedGas uint64, failed bo
 
 	// Pay intrinsic gas
 	gas, err := IntrinsicGas(st.data, contractCreation, homestead)
+	if err != nil {
+		return nil, 0, false, err
+	}
 	if err = st.useGas(gas); err != nil {
 		return nil, 0, false, err
 	}