Fix getCollaterals and getCollateralValue

[rramsden]

Context

I noticed since bETH was introduced Borrow class getCollaterals and getCollateralValue no longer function.

A case statement was introduced which broke functionality for AddressFromJsonProvider. Before this method just returned the custody contract address but now it can return a null value if the switch case on collateral doesn't match:

anchor.js/src/address-provider/from-json.ts

Lines 64 to 73 in a4b3da7

	custody(_denom: MARKET_DENOMS, collateral: COLLATERAL_DENOMS): string {
	switch (collateral) {
	case COLLATERAL_DENOMS.UBLUNA: {
	return this.data.mmCustody
	}
	case COLLATERAL_DENOMS.UBETH: {
	return this.data.mmCustodyBEth
	}
	}
	}

For example, when Borrow calls queryCustodyBorrower the parameter custody is passed with an instance of MARKET_DENOMS and not with the a collateral denomination:

anchor.js/src/facade/borrow/borrow.ts

Lines 126 to 130 in a4b3da7

	const userBalance = await queryCustodyBorrower({
	lcd: this._lcd,
	...getCollateralsOption,
	custody: getCollateralsOption.market,
	})(this._addressProvider);

Then custody is type-casted to type COLLATERAL_DENOMS and we just get a null value back from our switch case

anchor.js/src/queries/money-market/custody-borrower.ts

Lines 20 to 37 in a4b3da7

	export const queryCustodyBorrower = ({
	lcd,
	market,
	custody,
	address,
	}: Option) => async (
	addressProvider: AddressProvider,
	): Promise<BorrowerResponse> => {
	const custodyAddress = custody.startsWith('terra1')
	? custody
	: addressProvider.custody(market, custody as COLLATERAL_DENOMS);
	return lcd.wasm.contractQuery<BorrowerResponse>(custodyAddress, {
	borrower: {
	address: address,
	},
	});
	};

How to reproduce

You can see master branch no longer works running the following from node console:

let walletAddress = 'YOUR_TERRA_WALLET_ADDRESS'

const Terra = require('@terra-money/terra.js')
const AnchorJS = require('./dist/index')

const LCDClient = Terra.LCDClient
const Anchor = AnchorJS.Anchor
const columbus4 = AnchorJS.columbus4
const AddressProviderFromJson = AnchorJS.AddressProviderFromJson

let client = new LCDClient({
  URL: 'https://lcd.terra.dev',
  chainID: 'columbus-4'
})
let provider = new AddressProviderFromJson(columbus4)
let anchor = new Anchor(client, provider)

anchor.borrow.getCollaterals({ market: 'uusd', address: walletAddress }).then(console.log)
anchor.borrow.getCollateralValue({ market: 'uusd', address: walletAddress }).then(console.log)

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[rramsden]

There was a balance check here which returns null. It's a bit weird since if this condition is met you get something like the following back when this function is called:

[ null ]

Better to just return an actual entry e.g.

[
  {
    collateral: 'terra1....',
    balance: '0.000000000000000000'
  },
  {
    collateral: 'terra1....',
    balance: '0.000000000000000000'
  }
]

[rramsden]

Just my opinion but this was added to make these functions work properly again

[rramsden]

This can be safely removed if the null return is removed, see other comment