Fixed lookup of isConnected method

Author: devconcept

src/gridfs.ts

@@ -31,7 +31,6 @@ import {
 	UrlStorageOptions,
 	DbStorageOptions
 } from './types';
-import hasOwn from "has-own-prop";
 
 const isGeneratorFn = isGenerator.fn;
 
@@ -456,9 +455,10 @@ export class GridFsStorage extends EventEmitter implements StorageEngine {
 		}
 
 		if (this.client) {
-			this.connected = hasOwn(this.client, 'isConnected')
-				// @ts-ignore
-				? this.client.isConnected()
+			// @ts-ignore
+			this.connected = this.client.isConnected
+				? // @ts-ignore
+				  this.client.isConnected()
 				: true;
 			return;
 		}