feat(utxo-core): add utility function to check for taproot chain

Add `isTaprootChain` utility function to extract duplicate code and
improve maintainability.

Issue: BTC-2373

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

Author: davidkaplanbitgo

modules/utxo-core/src/bip322/toSpend.ts

@@ -1,6 +1,8 @@
 import { Hash } from 'fast-sha256';
 import { Psbt, Transaction, bitgo, networks } from '@bitgo/utxo-lib';
 
+import { isTaprootChain } from './utils';
+
 export const BIP322_TAG = 'BIP0322-signed-message';
 
 /**
@@ -74,8 +76,7 @@ export function buildToSpendTransactionFromChainAndIndex(
   message: string | Buffer,
   tag = BIP322_TAG
 ): Transaction<bigint> {
-  const taprootChains = [...bitgo.chainCodesP2tr, ...bitgo.chainCodesP2trMusig2];
-  if (taprootChains.some((tc) => tc === chain)) {
+  if (isTaprootChain(chain)) {
     throw new Error('BIP322 is not supported for Taproot script types.');
   }
 

modules/utxo-core/src/bip322/utils.ts

@@ -28,3 +28,8 @@ export function getBip322ProofInputIndex(psbt: utxolib.Psbt): number | undefined
 export function psbtIsBip322Proof(psbt: utxolib.Psbt): boolean {
   return getBip322ProofInputIndex(psbt) !== undefined;
 }
+
+export function isTaprootChain(chain: utxolib.bitgo.ChainCode): boolean {
+  const taprootChains = [...utxolib.bitgo.chainCodesP2tr, ...utxolib.bitgo.chainCodesP2trMusig2];
+  return taprootChains.some((tc) => tc === chain);
+}