diff --git a/extensions/typescript-language-features/src/extension.ts b/extensions/typescript-language-features/src/extension.ts
index dee3929baba..83bd22e3eca 100644
--- a/extensions/typescript-language-features/src/extension.ts
+++ b/extensions/typescript-language-features/src/extension.ts
@@ -9,19 +9,20 @@ import * as vscode from 'vscode';
 import { Api, getExtensionApi } from './api';
 import { CommandManager } from './commands/commandManager';
 import { registerBaseCommands } from './commands/index';
+import { ElectronServiceConfigurationProvider } from './configuration/configuration.electron';
 import { ExperimentationTelemetryReporter, IExperimentationTelemetryReporter } from './experimentTelemetryReporter';
 import { ExperimentationService } from './experimentationService';
 import { createLazyClientHost, lazilyActivateClient } from './lazyClientHost';
+import { Logger } from './logging/logger';
 import { nodeRequestCancellerFactory } from './tsServer/cancellation.electron';
 import { NodeLogDirectoryProvider } from './tsServer/logDirectoryProvider.electron';
+import { PluginManager } from './tsServer/plugins';
 import { ElectronServiceProcessFactory } from './tsServer/serverProcess.electron';
 import { DiskTypeScriptVersionProvider } from './tsServer/versionProvider.electron';
 import { ActiveJsTsEditorTracker } from './ui/activeJsTsEditorTracker';
-import { ElectronServiceConfigurationProvider } from './configuration/configuration.electron';
 import { onCaseInsensitiveFileSystem } from './utils/fs.electron';
-import { Logger } from './logging/logger';
+import { Lazy } from './utils/lazy';
 import { getPackageInfo } from './utils/packageInfo';
-import { PluginManager } from './tsServer/plugins';
 import * as temp from './utils/temp.electron';
 
 export function activate(
@@ -75,7 +76,7 @@ export function activate(
 	registerBaseCommands(commandManager, lazyClientHost, pluginManager, activeJsTsEditorTracker);
 
 	import('./task/taskProvider').then(module => {
-		context.subscriptions.push(module.register(lazyClientHost.map(x => x.serviceClient)));
+		context.subscriptions.push(module.register(new Lazy(() => lazyClientHost.value.serviceClient)));
 	});
 
 	import('./languageFeatures/tsconfig').then(module => {
diff --git a/extensions/typescript-language-features/src/lazyClientHost.ts b/extensions/typescript-language-features/src/lazyClientHost.ts
index 6d2bb34604f..3fc8a37cd17 100644
--- a/extensions/typescript-language-features/src/lazyClientHost.ts
+++ b/extensions/typescript-language-features/src/lazyClientHost.ts
@@ -16,7 +16,7 @@ import ManagedFileContextManager from './ui/managedFileContext';
 import { ServiceConfigurationProvider } from './configuration/configuration';
 import * as fileSchemes from './configuration/fileSchemes';
 import { standardLanguageDescriptions, isJsConfigOrTsConfigFileName } from './configuration/languageDescription';
-import { Lazy, lazy } from './utils/lazy';
+import { Lazy } from './utils/lazy';
 import { Logger } from './logging/logger';
 import { PluginManager } from './tsServer/plugins';
 
@@ -37,7 +37,7 @@ export function createLazyClientHost(
 	},
 	onCompletionAccepted: (item: vscode.CompletionItem) => void,
 ): Lazy<TypeScriptServiceClientHost> {
-	return lazy(() => {
+	return new Lazy(() => {
 		const clientHost = new TypeScriptServiceClientHost(
 			standardLanguageDescriptions,
 			context,
diff --git a/extensions/typescript-language-features/src/utils/lazy.ts b/extensions/typescript-language-features/src/utils/lazy.ts
index 23c000bc65d..7114ece99b1 100644
--- a/extensions/typescript-language-features/src/utils/lazy.ts
+++ b/extensions/typescript-language-features/src/utils/lazy.ts
@@ -3,37 +3,45 @@
  *  Licensed under the MIT License. See License.txt in the project root for license information.
  *--------------------------------------------------------------------------------------------*/
 
-export interface Lazy<T> {
-	value: T;
-	hasValue: boolean;
-	map<R>(f: (x: T) => R): Lazy<R>;
-}
+export class Lazy<T> {
 
-class LazyValue<T> implements Lazy<T> {
-	private _hasValue: boolean = false;
+	private _didRun: boolean = false;
 	private _value?: T;
+	private _error: Error | undefined;
 
 	constructor(
-		private readonly _getValue: () => T
+		private readonly executor: () => T,
 	) { }
 
+	/**
+	 * True if the lazy value has been resolved.
+	 */
+	get hasValue() { return this._didRun; }
+
+	/**
+	 * Get the wrapped value.
+	 *
+	 * This will force evaluation of the lazy value if it has not been resolved yet. Lazy values are only
+	 * resolved once. `getValue` will re-throw exceptions that are hit while resolving the value
+	 */
 	get value(): T {
-		if (!this._hasValue) {
-			this._hasValue = true;
-			this._value = this._getValue();
+		if (!this._didRun) {
+			try {
+				this._value = this.executor();
+			} catch (err) {
+				this._error = err;
+			} finally {
+				this._didRun = true;
+			}
+		}
+		if (this._error) {
+			throw this._error;
 		}
 		return this._value!;
 	}
 
-	get hasValue(): boolean {
-		return this._hasValue;
-	}
-
-	public map<R>(f: (x: T) => R): Lazy<R> {
-		return new LazyValue(() => f(this.value));
-	}
+	/**
+	 * Get the wrapped value without forcing evaluation.
+	 */
+	get rawValue(): T | undefined { return this._value; }
 }
-
-export function lazy<T>(getValue: () => T): Lazy<T> {
-	return new LazyValue<T>(getValue);
-}
\ No newline at end of file
diff --git a/extensions/typescript-language-features/src/utils/temp.electron.ts b/extensions/typescript-language-features/src/utils/temp.electron.ts
index cf099411246..84dd358b47c 100644
--- a/extensions/typescript-language-features/src/utils/temp.electron.ts
+++ b/extensions/typescript-language-features/src/utils/temp.electron.ts
@@ -6,7 +6,7 @@
 import * as fs from 'fs';
 import * as os from 'os';
 import * as path from 'path';
-import { lazy } from './lazy';
+import { Lazy } from './lazy';
 
 function makeRandomHexString(length: number): string {
 	const chars = ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'];
@@ -18,12 +18,12 @@ function makeRandomHexString(length: number): string {
 	return result;
 }
 
-const rootTempDir = lazy(() => {
+const rootTempDir = new Lazy(() => {
 	const filename = `vscode-typescript${process.platform !== 'win32' && process.getuid ? process.getuid() : ''}`;
 	return path.join(os.tmpdir(), filename);
 });
 
-export const instanceTempDir = lazy(() => {
+export const instanceTempDir = new Lazy(() => {
 	const dir = path.join(rootTempDir.value, makeRandomHexString(20));
 	fs.mkdirSync(dir, { recursive: true });
 	return dir;