fix: resolve some tokens not searchable by contract address in token selector cx bug (#4988)

* init

* ask zzmp question

* fixes omg

* remove comment

* comments

* respond to zzmp

* fix

src/constants/tokens.ts

@@ -6,6 +6,11 @@ import { SupportedChainId } from './chains'
 
 export const NATIVE_CHAIN_ID = 'NATIVE'
 
+// When decimals are not specified for an ERC20 token
+// use default ERC20 token decimals as specified here:
+// https://docs.openzeppelin.com/contracts/3.x/erc20
+export const DEFAULT_ERC20_DECIMALS = 18
+
 export const USDC_MAINNET = new Token(
   SupportedChainId.MAINNET,
   '0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48',

src/lib/hooks/useCurrency.ts

@@ -12,6 +12,7 @@ import useNativeCurrency from 'lib/hooks/useNativeCurrency'
 import { useEffect, useMemo, useState } from 'react'
 import { WrappedTokenInfo } from 'state/lists/wrappedTokenInfo'
 
+import { DEFAULT_ERC20_DECIMALS } from '../../constants/tokens'
 import { TOKEN_SHORTHANDS } from '../../constants/tokens'
 import { getContract, isAddress } from '../../utils'
 import { supportedChainId } from '../../utils/supportedChainId'
@@ -121,7 +122,8 @@ export function useTokenFromActiveNetwork(tokenAddress: string | undefined): Tok
     () => decimals.loading || symbol.loading || tokenName.loading,
     [decimals.loading, symbol.loading, tokenName.loading]
   )
-  const parsedDecimals = useMemo(() => decimals.result?.[0], [decimals.result])
+  const parsedDecimals = useMemo(() => decimals?.result?.[0] ?? DEFAULT_ERC20_DECIMALS, [decimals.result])
+
   const parsedSymbol = useMemo(
     () => parseStringOrBytes32(symbol.result?.[0], symbolBytes32.result?.[0], 'UNKNOWN'),
     [symbol.result, symbolBytes32.result]
@@ -134,9 +136,7 @@ export function useTokenFromActiveNetwork(tokenAddress: string | undefined): Tok
   return useMemo(() => {
     // If the token is on another chain, we cannot fetch it on-chain, and it is invalid.
     if (typeof tokenAddress !== 'string' || !isSupportedChain(chainId) || !formattedAddress) return undefined
-
     if (isLoading || !chainId) return null
-    if (!parsedDecimals) return undefined
 
     return new Token(chainId, formattedAddress, parsedDecimals, parsedSymbol, parsedName)
   }, [chainId, tokenAddress, formattedAddress, isLoading, parsedDecimals, parsedSymbol, parsedName])
@@ -152,7 +152,6 @@ type TokenMap = { [address: string]: Token }
 export function useTokenFromMapOrNetwork(tokens: TokenMap, tokenAddress?: string | null): Token | null | undefined {
   const address = isAddress(tokenAddress)
   const token: Token | undefined = address ? tokens[address] : undefined
-
   const tokenFromNetwork = useTokenFromActiveNetwork(token ? undefined : address ? address : undefined)
 
   return tokenFromNetwork ?? token

src/utils/index.ts

@@ -8,7 +8,9 @@ import { ChainTokenMap } from 'lib/hooks/useTokenList/utils'
 // returns the checksummed address if the address is valid, otherwise returns false
 export function isAddress(value: any): string | false {
   try {
-    return getAddress(value)
+    // Alphabetical letters must be made lowercase for getAddress to work.
+    // See documentation here: https://docs.ethers.io/v5/api/utils/address/
+    return getAddress(value.toLowerCase())
   } catch {
     return false
   }