KeyringController:signTransaction does not cover all check for valid transaction

`KeyringController:signTransaction` fails in scenario like

```
const signedTx = await keyringController.signTransaction({}, account);
```

But not in scenario like:

```
const txParams = {
// no txParams passed
};
const unsignedEthTx = TransactionFactory.fromTxData(txParams, {
common: new Common(commonConfig),
freeze: false,
});
expect(unsignedEthTx.v).toBeUndefined();
const signedTx = await keyringController.signTransaction(
unsignedEthTx,
account,
);
```

Also the error message passed for wrong transaction is not very useful.