fix: improve types, remove dead code

src/bundling.ts

@@ -36,7 +36,6 @@
 'use strict';
 
 import * as _ from 'lodash';
-import * as util from 'util';
 import {NormalApiCaller, APICall, PromiseCanceller, APICallback} from './api_callable';
 import {GoogleError} from './GoogleError';
 import {CallSettings} from './gax';

src/grpc.ts

@@ -80,7 +80,7 @@ const COMMON_PROTO_FILES =
 export {GrpcObject} from 'grpc';
 
 export interface GrpcClientOptions extends GoogleAuthOptions {
-  auth: GoogleAuth;
+  auth?: GoogleAuth;
   promise?: PromiseConstructor;
   grpc?: GrpcModule;
 }
@@ -135,11 +135,7 @@ export class GrpcClient {
    * promises will be used.
    * @constructor
    */
-  constructor(options: GrpcClientOptions) {
-    // if (!(this instanceof GrpcClient)) {
-    //   return new GrpcClient(options);
-    // }
-    options = options || {};
+  constructor(options: GrpcClientOptions = {}) {
     this.auth = options.auth || new GoogleAuth(options);
     this.promise = options.promise || Promise;
     if ('grpc' in options) {

src/index.ts

@@ -46,6 +46,7 @@ export {BundleDescriptor, BundleExecutor} from './bundling';
 export {PathTemplate} from './path_template';
 export {PageDescriptor} from './paged_iteration';
 export {createApiCall} from './api_callable';
+export {GoogleError} from './GoogleError';
 export {ClientStub, ClientStubOptions, GrpcClient, GrpcClientOptions, GrpcModule, GrpcObject, GoogleProtoFilesRoot, Metadata, MetadataValue} from './grpc';
 
 function lro(options: GrpcClientOptions) {

src/longrunning.ts

@@ -29,10 +29,7 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-import * as events from 'events';
 import {EventEmitter} from 'events';
-import * as util from 'util';
-
 import {APICall, APICallback, CancellablePromise, NormalApiCaller, PromiseCanceller} from './api_callable';
 import {BackoffSettings, CallOptions, createBackoffSettings} from './gax';
 import {GoogleError} from './GoogleError';

src/operations_client.ts

@@ -27,7 +27,6 @@
 /* jscs: disable maximumLineLength */
 'use strict';
 
-import * as path from 'path';
 import * as extend from 'extend';
 import * as apiCallable from './api_callable';
 import * as gax from './gax';

system-test/system.ts

@@ -21,18 +21,11 @@ import * as rimraf from 'rimraf';
 import * as util from 'util';
 
 const mkdir = util.promisify(fs.mkdir);
-const readFile = util.promisify(fs.readFile);
-const writeFile = util.promisify(fs.writeFile);
 const rmrf = util.promisify(rimraf);
 
 const baseRepoUrl = 'https://github.com/googleapis/';
-const gaxPath = process.cwd();
 const testDir = path.join(process.cwd(), 'system-test-run');
 
-interface PackageJson {
-  dependencies: {[name: string]: string;};
-}
-
 interface ExecuteResult {
   stdout: string;
   stderr: string;

tsconfig.json

@@ -4,8 +4,7 @@
     "rootDir": ".",
     "outDir": "build",
     "noImplicitAny": false,
-    "noImplicitThis": false,
-    "target": "es5"
+    "noImplicitThis": false
   },
   "include": [
     "src/*.ts",