feat(abstract-utxo): add getKeySignatures function

The lodash method `_.get` does not do any type checking, so let's not use it.

Issue: BTC-1450

Author: OttoAllmendinger

modules/abstract-utxo/src/keychains.ts

@@ -1,9 +1,10 @@
+import assert from 'assert';
 import * as t from 'io-ts';
 import * as utxolib from '@bitgo/utxo-lib';
 import { IRequestTracer, IWallet, KeyIndices, promiseProps, Triple } from '@bitgo/sdk-core';
 
 import { AbstractUtxoCoin } from './abstractUtxoCoin';
-import assert from 'assert';
+import { UtxoWallet } from './wallet';
 
 /*
 
@@ -64,3 +65,17 @@ export async function fetchKeychains(
   assert(UtxoNamedKeychains.is(result));
   return result;
 }
+
+export const KeySignatures = t.partial({
+  backupPub: t.string,
+  bitgoPub: t.string,
+});
+
+export type KeySignatures = t.TypeOf<typeof KeySignatures>;
+
+export function getKeySignatures(wallet: UtxoWallet): KeySignatures | undefined {
+  if (t.partial({ keySignatures: KeySignatures }).is(wallet._wallet)) {
+    return wallet._wallet.keySignatures;
+  }
+  return undefined;
+}

modules/abstract-utxo/src/transaction/fixedScript/parseTransaction.ts

@@ -11,7 +11,7 @@ import {
   ParsedTransaction,
   ParseTransactionOptions,
 } from '../../abstractUtxoCoin';
-import { fetchKeychains, toKeychainTriple, UtxoKeychain, UtxoNamedKeychains } from '../../keychains';
+import { fetchKeychains, getKeySignatures, toKeychainTriple, UtxoKeychain, UtxoNamedKeychains } from '../../keychains';
 
 /**
  * @param first
@@ -206,7 +206,7 @@ export async function parseTransaction<TNumber extends bigint | number>(
 
   return {
     keychains,
-    keySignatures: _.get(wallet, '_wallet.keySignatures', {}),
+    keySignatures: getKeySignatures(wallet) ?? {},
     outputs: allOutputDetails,
     missingOutputs,
     explicitExternalOutputs,