Building Rariable


from this repo I try to learn more about NFT mintings
on line 180

const receipt = await tokenContract.methods.createItem(metadataUrl).send({from: ethereum.selectedAddress});
Question is ::
What is this “ethereum.selectedAddress” and is it diffrenet from const userAddress = user.get(“ethAddress”);

because when I console them they were same
why this question because in first time when we login and refreshes once ethereum.selectedAddress not exist hence errors comes but we this works on first refresh user.get(“ethAddress”);

may some JS issue from my side

Question 2

if I deploy my contract in Mumbai Testnet and and when user / me try to there NFT with Rinkeby test net is that’s an error

Because when I try to do same this error comes
Transaction Error. Exception thrown in contract code.