Remove unused instance variable

packages/subproviders/src/subproviders/ledger.ts

@@ -32,7 +32,6 @@ const DEFAULT_ADDRESS_SEARCH_LIMIT = 1000;
  */
 export class LedgerSubprovider extends BaseWalletSubprovider {
     // tslint:disable-next-line:no-unused-variable
-    private readonly _nonceLock = new Lock();
     private readonly _connectionLock = new Lock();
     private readonly _networkId: number;
     private _baseDerivationPath: string;