Uncaught (in promise) BigNumber Error for address - solidity

Question

I have a function in ERC721 contract which returns an address.
I am passing the returned address to ERC20 transferFrom function, and getting the following error.
My javascript code
Voting.deployed().then(function(ERC20Instance) {
let buyerAddress = $("#to-address").val();
ERC20Instance.approve(buyerAddress, 100, {gas: 1000000, from: web3.eth.accounts[0]});
ERC20Instance.transferFrom(buyerAddress, contractInstance.getCreator(), 10, {gas: 1000000, from: web3.eth.accounts[0]});
^^^^This line is causing an error.
})
and ERC721 contract:
function getCreator() public view returns (address) {
return nftInfo[owner].creator;
}
function mint(string calldata nftName) external payable {
uint256 newItemId = _tokenIds.current();
_mint(msg.sender, newItemId);
owner = msg.sender;
nftInfo[msg.sender].nftId = newItemId;
nftInfo[msg.sender].name = nftName;
nftInfo[msg.sender].creator = msg.sender;
allValidTokenIndex[newItemId] = allValidTokenIds.length;
allValidTokenIds.push(newItemId);
_tokenIds.increment();
}

Answer 1

contractInstance.getCreator()
This JS function returns a Promise - not the actual address. You need to resolve the Promise first to get the address.
Same goes with the approve() function. You should wait until the function has been processed (i.e. after the JS Promise has been resolved) to prevent unexpected behavior resulting from the transferFrom() being executed asynchronously before the approve() finishes running.
Voting.deployed().then(async function(ERC20Instance) { // add `async`
let buyerAddress = $("#to-address").val();
await ERC20Instance.approve( // recommended: add `await`
buyerAddress,
100,
{gas: 1000000, from: web3.eth.accounts[0]}
);
await ERC20Instance.transferFrom( // recommended: add `await`
buyerAddress,
await contractInstance.getCreator(), // add `await`
10,
{gas: 1000000, from: web3.eth.accounts[0]}
);