Set to/from token prices to zero if CoinGecko price fetch fails

[cgewecke]

Especially on Polygon, CoinGecko price requests return an empty object for some (liquid) tokens, crashing the quote API

In the initial TradeQuoter review Alex suggested we set the price as 0 when this happens as a way of failing gracefully. (#61).

Would that work for set-ui, or is there a more convenient default value?

Example response with zero values:

{
  from: '0x1494ca1f11d487c2bbe4543e90080aeba4ba3c2b',
  fromTokenAddress: '0x9f8f72aa9304c8b593d555f12ef6589cc3a579a2',
  toTokenAddress: '0x9f8f72aa9304c8b593d555f12ef6589cc3a579a2',
  exchangeAdapterName: 'ZeroExApiAdapterV4',
  calldata: '0x415565b00000000000000000000000009f8f72aa9304c8b593d555f12ef6589cc3a579a2',
  gas: '315000',
  gasPrice: '61',
  slippagePercentage: '2.00%',
  fromTokenAmount: '1126868991563',
  toTokenAmount: '90314741816',
  display: {
    inputAmountRaw: '.5',
    inputAmount: '500000000000000000',
    quoteAmount: '499999999999793729',
    fromTokenDisplayAmount: '0.4999999999997937',
    toTokenDisplayAmount: '0.04131269116050703',
+    fromTokenPriceUsd: '$0.00', 
+    toTokenPriceUsd: '$0.00', 
+    gasCostsUsd: '$0.00', 
    gasCostsChainCurrency: '0.0192150 ETH',
    feePercentage: '1.00%',
+    slippage: '0.00%', 
  },
},

[asoong]

This is fine for now, something to add as an issue:

• We don't want this to block the quote generation, but we want to provide a signal that one or more of the dependencies may be inaccurate
• We should be able to capture some kind of status on the API calls each time a dependency is down, adding a new field for each dependency so the consumer knows which data may be using defaults