SubmittedTransaction::gas() in the published pallet-revive-eth-rpc crate (exposed via pub mod example; with no feature gate) unwraps an Option<U256> and panics when the underlying GenericTransaction has no gas field set, which is a legitimate state since GenericTransaction::gas is Option<U256> for legacy/incomplete payloads and the constructor never enforces gas-is-set; the fix is to change the return type to Option<U256> to match the underlying field and update the in-crate wait_for_receipt assertion to handle the None case.