paysWithFeeOrigin? optional input seems to be broken

[IkerAlus]

If I construct a payload with the paysWithFeeOrigin? optional input as an integer (Asset Hub as origin), the API creates it with a zero asset ID is XCM location. The expected behaviour should be to error out saying the input is not a valid asset ID.

• Steps to reproduce: Run the assetHubToMoonriverPaysWithFeeOrigin.ts example.

Also, if I change the ID to a different integer (an integer not registered as a sufficient asset), the API returns the error "InvalidAsset: asset with assetId {assetID} is not a sufficient asset to pay for fees" which is misleading. The error should point to the fact that there is no liquidity pool of the given asset in the asset conversion pallet or simply say that the input is not a valid asset ID. Asset sufficiency is not relevant anymore in Kusama and Polkadot Asset Hubs to pay fees.

Extra: paysWithFeeOrigin? optional input doesn't allow to pass asset symbols like USDT, it would be nice to add this enhancement.