Strictly Explicit: Enable TypeScript strict mode

.eslintrc.js

@@ -27,6 +27,15 @@ module.exports = {
     // The rule is also mostly irrelevant to this codebase due to TypeScript
     // usage (where .tsx is required).
     "react/jsx-filename-extension": [0],
+    // TypeScript allows us to declare props that are non-optional internally
+    // but are interpreted as optional externally if they have defaultProps
+    // defined; the following two adjustments disable eslint-plugin-react
+    // checks that predate this ability for TS and that no longer apply.
+    "react/default-props-match-prop-types": [
+      2,
+      { allowRequiredDefaults: true },
+    ],
+    "react/require-default-props": [0],
     // Shared components may have labels associated externally in a way ESLint
     // does not detect.
     "jsx-a11y/label-has-associated-control": [

background/lib/alchemy.ts

@@ -1,4 +1,3 @@
-import Ajv, { JTDDataType } from "ajv/dist/jtd"
 import {
   AlchemyProvider,
   AlchemyWebSocketProvider,
@@ -8,8 +7,7 @@ import { utils } from "ethers"
 import logger from "./logger"
 import { AssetTransfer, HexString, SmartContractFungibleAsset } from "../types"
 import { ETH, ETHEREUM } from "../constants"
-
-const ajv = new Ajv()
+import { jtdValidatorFor } from "./validation"
 
 // JSON Type Definition for the Alchemy assetTransfers API.
 // https://docs.alchemy.com/alchemy/documentation/enhanced-apis/transfers-api
@@ -45,12 +43,9 @@ const alchemyGetAssetTransfersJTD = {
   },
 } as const
 
-type AlchemyAssetTransferResponse = JTDDataType<
-  typeof alchemyGetAssetTransfersJTD
->
-
-const isValidAlchemyAssetTransferResponse =
-  ajv.compile<AlchemyAssetTransferResponse>(alchemyGetAssetTransfersJTD)
+const isValidAlchemyAssetTransferResponse = jtdValidatorFor(
+  alchemyGetAssetTransfersJTD
+)
 
 /**
  * Use Alchemy's getAssetTransfers call to get historical transfers for an
@@ -144,7 +139,7 @@ export async function getAssetTransfers(
         dataSource: "alchemy",
       } as AssetTransfer
     })
-    .filter((t) => t)
+    .filter((t): t is AssetTransfer => t !== null)
 }
 
 // JSON Type Definition for the Alchemy token balance API.
@@ -167,10 +162,9 @@ const alchemyTokenBalanceJTD = {
   additionalProperties: false,
 } as const
 
-type AlchemyTokenBalanceResponse = JTDDataType<typeof alchemyTokenBalanceJTD>
-
-const isValidAlchemyTokenBalanceResponse =
-  ajv.compile<AlchemyTokenBalanceResponse>(alchemyTokenBalanceJTD)
+const isValidAlchemyTokenBalanceResponse = jtdValidatorFor(
+  alchemyTokenBalanceJTD
+)
 
 /**
  * Use Alchemy's getTokenBalances call to get balances for a particular address.
@@ -204,7 +198,16 @@ export async function getTokenBalances(
 
   // TODO log balances with errors, consider returning an error type
   return json.tokenBalances
-    .filter((b) => b.error === null && b.tokenBalance !== null)
+    .filter(
+      (
+        b
+      ): b is typeof json["tokenBalances"][0] & {
+        tokenBalance: Exclude<
+          typeof json["tokenBalances"][0]["tokenBalance"],
+          null
+        >
+      } => b.error === null && b.tokenBalance !== null
+    )
     .map((tokenBalance) => ({
       contractAddress: tokenBalance.contractAddress,
       amount:
@@ -228,10 +231,9 @@ const alchemyTokenMetadataJTD = {
   additionalProperties: false,
 } as const
 
-type AlchemyTokenMetadataResponse = JTDDataType<typeof alchemyTokenMetadataJTD>
-
-const isValidAlchemyTokenMetadataResponse =
-  ajv.compile<AlchemyTokenMetadataResponse>(alchemyTokenMetadataJTD)
+const isValidAlchemyTokenMetadataResponse = jtdValidatorFor(
+  alchemyTokenMetadataJTD
+)
 
 /**
  * Use Alchemy's getTokenMetadata call to get metadata for a token contract on
@@ -262,8 +264,8 @@ export async function getTokenMetadata(
     name: json.name,
     symbol: json.symbol,
     metadata: {
-      logoURL: json.logo,
       tokenLists: [],
+      ...(json.logo ? { logoURL: json.logo } : {}),
     },
     homeNetwork: ETHEREUM, // TODO make multi-network friendly
     contractAddress,

background/lib/logger.ts

@@ -58,7 +58,7 @@ function genericLogger(level: LogLevel, input: unknown[]) {
 
   console.log(...input)
 
-  const stackTrace = new Error().stack.split("\n").filter((line) => {
+  const stackTrace = new Error().stack?.split("\n")?.filter((line) => {
     // Remove empty lines from the output
     // Chrome prepends the word "Error" to the first line of the trace, but Firefox doesn't
     // Let's ignore that for consistency between browsers!
@@ -69,9 +69,11 @@ function genericLogger(level: LogLevel, input: unknown[]) {
     return true
   })
 
-  // The first two lines of the stack trace will always be generated by this
-  // file, so let's ignore them.
-  console.log(stackTrace.slice(2).join("\n"))
+  if (typeof stackTrace !== "undefined") {
+    // The first two lines of the stack trace will always be generated by this
+    // file, so let's ignore them.
+    console.log(stackTrace.slice(2).join("\n"))
+  }
   console.groupEnd()
 }
 

background/lib/prices.ts

@@ -13,7 +13,7 @@ const COINGECKO_API_ROOT = "https://api.coingecko.com/api/v3"
 export async function getPrice(
   coingeckoCoinId = "ethereum",
   currencySymbol = "usd"
-): Promise<number> {
+): Promise<number | null> {
   const url = `${COINGECKO_API_ROOT}/simple/price?ids=${coingeckoCoinId}&vs_currencies=${currencySymbol}&include_last_updated_at=true`
 
   const json = await fetchJson(url)
@@ -29,11 +29,7 @@ export async function getPrice(
     return null
   }
 
-  return json
-    ? parseFloat(
-        json[coingeckoCoinId][currencySymbol] as string // FIXME Drop as when strict mode arrives and price schema type can include this.
-      )
-    : null
+  return json?.[coingeckoCoinId]?.[currencySymbol] || null
 }
 
 function multiplyByFloat(n: bigint, f: number, precision: number) {
@@ -67,34 +63,32 @@ export async function getPrices(
       validate.errors
     )
 
-    return null
+    return []
   }
 
-  return assets.reduce((acc, asset) => {
+  const resolutionTime = Date.now()
+  return assets.flatMap((asset) => {
     const simpleCoinPrices = json[asset.metadata.coinGeckoId]
-    return acc.concat(
-      vsCurrencies
-        .map((c) => {
-          const symbol = c.symbol.toLowerCase()
-          if (symbol in simpleCoinPrices) {
-            return {
-              pair: [c, asset],
-              amounts: [
-                multiplyByFloat(
-                  BigInt(10) ** BigInt(c.decimals),
-                  simpleCoinPrices[symbol] as number, // FIXME Drop as when strict mode arrives and price schema type can include this.
-                  8
-                ),
-                BigInt(1),
-              ],
-              time: Date.now(),
-            } as PricePoint
+
+    return vsCurrencies
+      .map<PricePoint | undefined>((c) => {
+        const symbol = c.symbol.toLowerCase()
+        const coinPrice = simpleCoinPrices?.[symbol]
+
+        if (coinPrice) {
+          return {
+            pair: [c, asset],
+            amounts: [
+              multiplyByFloat(BigInt(10) ** BigInt(c.decimals), coinPrice, 8),
+              BigInt(1),
+            ],
+            time: resolutionTime,
           }
-          return undefined
-        })
-        .filter((p) => p)
-    )
-  }, [])
+        }
+        return undefined
+      })
+      .filter((p): p is PricePoint => p !== undefined)
+  })
 }
 
 /*

background/lib/tokenList.ts

@@ -86,9 +86,10 @@ export function networkAssetsFromLists(
         metadata: {
           ...original.metadata,
           ...asset.metadata,
-          tokenLists: original.metadata.tokenLists.concat(
-            asset.metadata.tokenLists
-          ),
+          tokenLists:
+            original.metadata?.tokenLists?.concat(
+              asset.metadata?.tokenLists ?? []
+            ) ?? [],
         },
       }
     } else {
@@ -99,7 +100,7 @@ export function networkAssetsFromLists(
 
   const merged = fungibleAssets.reduce(tokenReducer, {})
   return Object.entries(merged)
-    .map(([k, v]) => v)
+    .map(([, v]) => v)
     .slice()
     .sort((a, b) =>
       (a.metadata?.tokenLists?.length || 0) >