Invalid object key when sending transaction

[4xMafole]

Describe the bug
I get this problem when I create a custom transaction request and try to send it using the provider's signer.

To Reproduce
Steps to reproduce the behavior:

1. Create a custom transaction request

     final TransactionRequest transactionRequest = TransactionRequest(
      to: null,
      from: await provider!.getSigner().getAddress(),
      data: data,
      gasLimit: BigInt.from(2000000),
      maxFeePerGas: null,
      maxPriorityFeePerGas: null,
    );

2. send the transaction using the current provider's signer

    final transaction =
        await provider!.getSigner().sendTransaction(transactionRequest);

    final signature = await transaction.wait();

    return signature.transactionHash;

3. Error
   You'll end up having this error on the console:

Error: EthersException: INVALID_ARGUMENT invalid object key - maxFeePerGas
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/errors.dart 266:49  throw_
packages/flutter_web3/src/ethers/signer.dart 72:13                                                                         sendTransaction

Expected behavior
The expectation is to send the transaction and return the appropriate transaction hash.

Additional context
I did a research about the problem and found out this issue here on ethers.js repository. As the solution is to add a field named type but seems the TransactionRequest class does not have that field.