fix(wasm-utxo): add proper TypeScript type assertions

Improve type safety by adding explicit type assertions and proper type
handling for node and object structures. This fixes potential TypeScript
errors with JSON stringification of nodes, unknown types, and array
indexing. Also improves error message display by properly serializing
objects to strings.

Issue: BTC-2786

Co-authored-by: llm-git <[email protected]>

Author: OttoAllmendinger

packages/wasm-utxo/js/ast/formatNode.ts

@@ -88,16 +88,16 @@ function formatN(n: Node | Node[]): string {
   if (n && typeof n === "object") {
     const entries = Object.entries(n);
     if (entries.length !== 1) {
-      throw new Error(`Invalid node: ${n}`);
+      throw new Error(`Invalid node: ${JSON.stringify(n)}`);
     }
-    const [name, value] = entries[0];
+    const [name, value] = entries[0] as [string, Node | Node[]];
     if (name === "tr" && Array.isArray(value)) {
-      const [key, tree] = value;
+      const [key, tree] = value as [Node, TapTree];
       return formatN({ tr: formatN([key, formatTr(tree)]) });
     }
     return `${name}(${formatN(value)})`;
   }
-  throw new Error(`Invalid node: ${n}`);
+  throw new Error(`Invalid node: ${JSON.stringify(n)}`);
 }
 
 export type TapTreeNode = TapTree;

packages/wasm-utxo/js/ast/fromWasmNode.ts

@@ -86,15 +86,16 @@ function fromUnknown(v: unknown): Node | Node[] {
         return node("and_v", value);
       case "AndB":
         return node("and_b", value);
-      case "AndOr":
+      case "AndOr": {
         if (!Array.isArray(value)) {
           throw new Error(`Invalid AndOr node: ${JSON.stringify(value)}`);
         }
-        const [cond, success, failure] = value;
+        const [cond, success, failure] = value as [unknown, unknown, unknown];
         if (failure === false) {
           return node("and_n", [cond, success]);
         }
         return node("andor", [cond, success, failure]);
+      }
 
       // Disjunctions
       case "OrB":

packages/wasm-utxo/js/fixedScriptWallet.ts

@@ -112,7 +112,10 @@ export class BitGoPsbt {
     walletKeys: WalletKeys,
     replayProtection: ReplayProtection,
   ): ParsedTransaction {
-    return this.wasm.parse_transaction_with_wallet_keys(walletKeys, replayProtection);
+    return this.wasm.parse_transaction_with_wallet_keys(
+      walletKeys,
+      replayProtection,
+    ) as ParsedTransaction;
   }
 
   /**
@@ -127,7 +130,7 @@ export class BitGoPsbt {
    * @note This method does NOT validate wallet inputs. It only parses outputs.
    */
   parseOutputsWithWalletKeys(walletKeys: WalletKeys): ParsedOutput[] {
-    return this.wasm.parse_outputs_with_wallet_keys(walletKeys);
+    return this.wasm.parse_outputs_with_wallet_keys(walletKeys) as ParsedOutput[];
   }
 
   /**

packages/wasm-utxo/js/index.ts

@@ -27,6 +27,7 @@ declare module "./wasm/wasm_utxo.js" {
     node(): unknown;
   }
 
+  // eslint-disable-next-line @typescript-eslint/no-namespace
   namespace WrapDescriptor {
     function fromString(descriptor: string, pkType: DescriptorPkType): WrapDescriptor;
     function fromStringDetectType(descriptor: string): WrapDescriptor;
@@ -37,6 +38,7 @@ declare module "./wasm/wasm_utxo.js" {
     node(): unknown;
   }
 
+  // eslint-disable-next-line @typescript-eslint/no-namespace
   namespace WrapMiniscript {
     function fromString(miniscript: string, ctx: ScriptContext): WrapMiniscript;
     function fromBitcoinScript(script: Uint8Array, ctx: ScriptContext): WrapMiniscript;

packages/wasm-utxo/test/address/utxolibCompat.ts

@@ -73,7 +73,7 @@ async function getFixtures(name: string, addressFormat?: AddressFormat): Promise
   const filename = addressFormat ? `${name}-${addressFormat}` : name;
   const fixturePath = path.join(__dirname, "..", "fixtures", "address", `${filename}.json`);
   const fixtures = await fs.readFile(fixturePath, "utf8");
-  return JSON.parse(fixtures);
+  return JSON.parse(fixtures) as Fixture[];
 }
 
 function runTest(network: utxolib.Network, addressFormat?: AddressFormat) {
@@ -85,9 +85,9 @@ function runTest(network: utxolib.Network, addressFormat?: AddressFormat) {
       fixtures = await getFixtures(name, addressFormat);
     });
 
-    it("should convert to utxolib compatible network", async function () {
+    it("should convert to utxolib compatible network", function () {
       for (const fixture of fixtures) {
-        const [_type, script, addressRef] = fixture;
+        const [, script, addressRef] = fixture;
         const scriptBuf = Buffer.from(script, "hex");
         const address = utxolibCompat.fromOutputScript(scriptBuf, network, addressFormat);
         assert.strictEqual(address, addressRef);
@@ -96,11 +96,11 @@ function runTest(network: utxolib.Network, addressFormat?: AddressFormat) {
       }
     });
 
-    it("should convert using coin name", async function () {
+    it("should convert using coin name", function () {
       const coinName = getCoinNameForNetwork(name);
 
       for (const fixture of fixtures) {
-        const [_type, script, addressRef] = fixture;
+        const [, script, addressRef] = fixture;
         const scriptBuf = Buffer.from(script, "hex");
 
         // Test encoding (script -> address)

packages/wasm-utxo/test/descriptorUtil.ts

@@ -5,10 +5,10 @@ import { DescriptorNode, MiniscriptNode, formatNode } from "../js/ast/index.js";
 
 async function assertEqualJSON(path: string, value: unknown): Promise<void> {
   try {
-    const data = JSON.parse(await fs.readFile(path, "utf8"));
+    const data: unknown = JSON.parse(await fs.readFile(path, "utf8"));
     assert.deepStrictEqual(data, value);
-  } catch (e: any) {
-    if (e.code === "ENOENT") {
+  } catch (e: unknown) {
+    if (typeof e === "object" && e !== null && "code" in e && e.code === "ENOENT") {
       await fs.writeFile(path, JSON.stringify(value, null, 2));
       throw new Error("Expected file not found, wrote it instead");
     }

packages/wasm-utxo/test/fixedScript/fixtureUtil.ts

@@ -89,7 +89,7 @@ export type Fixture = {
   psbtInputsFinalized: PsbtInput[] | null;
   outputs: Output[];
   psbtOutputs: PsbtOutput[];
-  extractedTransaction: any | null;
+  extractedTransaction: string | null;
 };
 
 /**

packages/wasm-utxo/test/fixedScript/verifySignature.ts

@@ -47,7 +47,7 @@ function getExpectedSignatures(
       // Regular multisig uses user + bitgo
       return { user: true, backup: false, bitgo: true };
     default:
-      throw new Error(`Unknown signature stage: ${signatureStage}`);
+      throw new Error(`Unknown signature stage: ${String(signatureStage)}`);
   }
 }
 

packages/wasm-utxo/test/fixtures.ts

@@ -1,11 +1,17 @@
 import * as fs from "fs/promises";
 export async function getFixture(path: string, defaultValue: unknown): Promise<unknown> {
   try {
-    return JSON.parse(await fs.readFile(path, "utf8"));
+    return JSON.parse(await fs.readFile(path, "utf8")) as unknown;
   } catch (e) {
-    if (e.code === "ENOENT") {
+    if (
+      typeof e === "object" &&
+      e !== null &&
+      "code" in e &&
+      (e as { code: unknown }).code === "ENOENT"
+    ) {
       await fs.writeFile(path, JSON.stringify(defaultValue, null, 2));
       throw new Error(`Fixture not found at ${path}, created a new one`);
     }
+    throw e;
   }
 }

packages/wasm-utxo/test/psbt.util.ts

@@ -79,16 +79,14 @@ function matchPath(path: (string | number)[], pattern: (string | number | symbol
   return true;
 }
 
-function normalizeBip32Derivation(v: unknown) {
+function normalizeBip32Derivation(v: unknown): {
+  masterFingerprint: Buffer;
+  path: string;
+}[] {
   if (!Array.isArray(v)) {
     throw new Error("Expected bip32Derivation to be an array");
   }
-  return (
-    [...v] as {
-      masterFingerprint: Buffer;
-      path: string;
-    }[]
-  )
+  return (v as { masterFingerprint: Buffer; path: string }[])
     .map((e) => {
       let { path } = e;
       if (path.startsWith("m/")) {
@@ -102,7 +100,7 @@ function normalizeBip32Derivation(v: unknown) {
     .sort((a, b) => a.masterFingerprint.toString().localeCompare(b.masterFingerprint.toString()));
 }
 
-function toPlainObject(v: unknown, path: (string | number)[]) {
+function toPlainObject(v: unknown, path: (string | number)[]): unknown {
   // psbts have fun getters and other types of irregular properties that we mash into shape here
   if (v === null || v === undefined) {
     return v;