diff --git a/tree-view-sample/src/fileExplorer.ts b/tree-view-sample/src/fileExplorer.ts
index 9b1870de..845efae5 100644
--- a/tree-view-sample/src/fileExplorer.ts
+++ b/tree-view-sample/src/fileExplorer.ts
@@ -296,12 +296,9 @@ export class FileSystemProvider implements vscode.TreeDataProvider<Entry>, vscod
 }
 
 export class FileExplorer {
-
-	private fileExplorer: vscode.TreeView<Entry>;
-
 	constructor(context: vscode.ExtensionContext) {
 		const treeDataProvider = new FileSystemProvider();
-		this.fileExplorer = vscode.window.createTreeView('fileExplorer', { treeDataProvider });
+		context.subscriptions.push(vscode.window.createTreeView('fileExplorer', { treeDataProvider }));
 		vscode.commands.registerCommand('fileExplorer.openFile', (resource) => this.openResource(resource));
 	}
 
diff --git a/tree-view-sample/src/ftpExplorer.ts b/tree-view-sample/src/ftpExplorer.ts
index c6097fe4..4c673dfd 100644
--- a/tree-view-sample/src/ftpExplorer.ts
+++ b/tree-view-sample/src/ftpExplorer.ts
@@ -15,9 +15,6 @@ export interface FtpNode {
 }
 
 export class FtpModel {
-
-	private nodes: Map<string, FtpNode> = new Map<string, FtpNode>();
-
 	constructor(readonly host: string, private user: string, private password: string) {
 	}
 
diff --git a/tree-view-sample/src/jsftp.d.ts b/tree-view-sample/src/jsftp.d.ts
index 6d23834d..a2db1146 100644
--- a/tree-view-sample/src/jsftp.d.ts
+++ b/tree-view-sample/src/jsftp.d.ts
@@ -5,7 +5,6 @@ import { EventEmitter } from 'events';
 
 declare namespace JSFtp {
 
-
     interface JSFtpOptions {
         host: string;
         port?: number | 21;
@@ -18,7 +17,6 @@ declare namespace JSFtp {
         (err: any, result: T): void;
     }
 
-
     interface Entry {
         name: string;
         size: number;
diff --git a/tree-view-sample/src/testView.ts b/tree-view-sample/src/testView.ts
index d4895c1c..46dfff96 100644
--- a/tree-view-sample/src/testView.ts
+++ b/tree-view-sample/src/testView.ts
@@ -4,6 +4,7 @@ export class TestView {
 
 	constructor(context: vscode.ExtensionContext) {
 		const view = vscode.window.createTreeView('testView', { treeDataProvider: aNodeWithIdTreeDataProvider(), showCollapseAll: true });
+		context.subscriptions.push(view);
 		vscode.commands.registerCommand('testView.reveal', async () => {
 			const key = await vscode.window.showInputBox({ placeHolder: 'Type the label of the item to reveal' });
 			if (key) {
diff --git a/tree-view-sample/yarn.lock b/tree-view-sample/yarn.lock
index 19af6bd7..a4e0fb8d 100644
--- a/tree-view-sample/yarn.lock
+++ b/tree-view-sample/yarn.lock
@@ -989,10 +989,10 @@ type-fest@^0.8.1:
   resolved "https://registry.yarnpkg.com/type-fest/-/type-fest-0.8.1.tgz#09e249ebde851d3b1e48d27c105444667f17b83d"
   integrity sha512-4dbzIzqvjtgiM5rw1k5rEHtBANKmdudhGyBEajN01fEyhaAIhsoKNy6y7+IN93IfpFtwY9iqi7kD+xwKhQsNJA==
 
-typescript@^3.9.4:
-  version "3.9.7"
-  resolved "https://registry.yarnpkg.com/typescript/-/typescript-3.9.7.tgz#98d600a5ebdc38f40cb277522f12dc800e9e25fa"
-  integrity sha512-BLbiRkiBzAwsjut4x/dsibSTB6yWpwT5qWmC2OfuCg3GgVQCSgMs4vEctYPhsaGtd0AeuuHMkjZ2h2WG8MSzRw==
+typescript@^4.0.2:
+  version "4.0.5"
+  resolved "https://registry.yarnpkg.com/typescript/-/typescript-4.0.5.tgz#ae9dddfd1069f1cb5beb3ef3b2170dd7c1332389"
+  integrity sha512-ywmr/VrTVCmNTJ6iV2LwIrfG1P+lv6luD8sUJs+2eI9NLGigaN+nUQc13iHqisq7bra9lnmUSYqbJvegraBOPQ==
 
 uri-js@^4.2.2:
   version "4.2.2"