diff --git a/src/vs/base/browser/ui/breadcrumbs/breadcrumbsWidget.ts b/src/vs/base/browser/ui/breadcrumbs/breadcrumbsWidget.ts
index 13e4b9c34be0848b36b077d48d9df43e040d93a2..2e72938f98677bd53a1cfeb6f5f9e8464b0b4926 100644
--- a/src/vs/base/browser/ui/breadcrumbs/breadcrumbsWidget.ts
+++ b/src/vs/base/browser/ui/breadcrumbs/breadcrumbsWidget.ts
@@ -77,8 +77,8 @@ export class BreadcrumbsWidget {
 	private _focusedItemIdx: number = -1;
 	private _selectedItemIdx: number = -1;
 
-	private _pendingLayout: IDisposable;
-	private _dimension: dom.Dimension;
+	private _pendingLayout: IDisposable | undefined;
+	private _dimension: dom.Dimension | undefined;
 
 	constructor(
 		container: HTMLElement
diff --git a/src/vs/base/common/event.ts b/src/vs/base/common/event.ts
index 2a42363714938042c9e044fa6ebb9a5137357aa7..4d43bd8c13208ba7f2dfdac5205b1765df882588 100644
--- a/src/vs/base/common/event.ts
+++ b/src/vs/base/common/event.ts
@@ -645,7 +645,7 @@ export interface IWaitUntil {
 
 export class AsyncEmitter<T extends IWaitUntil> extends Emitter<T> {
 
-	private _asyncDeliveryQueue: [Listener<T>, T, Promise<any>[]][];
+	private _asyncDeliveryQueue?: [Listener<T>, T, Promise<any>[]][];
 
 	async fireAsync(eventFn: (thenables: Promise<any>[], listener: Function) => T): Promise<void> {
 		if (!this._listeners) {
diff --git a/src/vs/editor/contrib/codelens/codelensWidget.ts b/src/vs/editor/contrib/codelens/codelensWidget.ts
index 24ed75a44056642023e9cd983a0372867d6d6715..2f34263e0fd49a3b1ee2d7bee97d479c9f09ce8b 100644
--- a/src/vs/editor/contrib/codelens/codelensWidget.ts
+++ b/src/vs/editor/contrib/codelens/codelensWidget.ts
@@ -60,7 +60,7 @@ class CodeLensContentWidget implements editorBrowser.IContentWidget {
 	private readonly _editor: editorBrowser.ICodeEditor;
 	private readonly _commands = new Map<string, Command>();
 
-	private _widgetPosition: editorBrowser.IContentWidgetPosition;
+	private _widgetPosition?: editorBrowser.IContentWidgetPosition;
 
 	constructor(
 		editor: editorBrowser.ICodeEditor,
@@ -147,8 +147,8 @@ class CodeLensContentWidget implements editorBrowser.IContentWidget {
 		};
 	}
 
-	getPosition(): editorBrowser.IContentWidgetPosition {
-		return this._widgetPosition;
+	getPosition(): editorBrowser.IContentWidgetPosition | null {
+		return this._widgetPosition || null;
 	}
 
 	isVisible(): boolean {
diff --git a/src/vs/editor/contrib/documentSymbols/outlineTree.ts b/src/vs/editor/contrib/documentSymbols/outlineTree.ts
index a77c8d1bd2e13b7c035b12f5a7309e4ab1448420..365b3e45c13996ece4c0e8d1ee1cba58c2a990bf 100644
--- a/src/vs/editor/contrib/documentSymbols/outlineTree.ts
+++ b/src/vs/editor/contrib/documentSymbols/outlineTree.ts
@@ -45,16 +45,19 @@ export class OutlineIdentityProvider implements IIdentityProvider<OutlineItem> {
 
 export class OutlineGroupTemplate {
 	static id = 'OutlineGroupTemplate';
-
-	labelContainer: HTMLElement;
-	label: HighlightedLabel;
+	constructor(
+		readonly labelContainer: HTMLElement,
+		readonly label: HighlightedLabel,
+	) { }
 }
 
 export class OutlineElementTemplate {
 	static id = 'OutlineElementTemplate';
-	container: HTMLElement;
-	iconLabel: IconLabel;
-	decoration: HTMLElement;
+	constructor(
+		readonly container: HTMLElement,
+		readonly iconLabel: IconLabel,
+		readonly decoration: HTMLElement,
+	) { }
 }
 
 export class OutlineVirtualDelegate implements IListVirtualDelegate<OutlineItem> {
@@ -80,7 +83,7 @@ export class OutlineGroupRenderer implements ITreeRenderer<OutlineGroup, FuzzySc
 		const labelContainer = dom.$('.outline-element-label');
 		dom.addClass(container, 'outline-element');
 		dom.append(container, labelContainer);
-		return { labelContainer, label: new HighlightedLabel(labelContainer, true) };
+		return new OutlineGroupTemplate(labelContainer, new HighlightedLabel(labelContainer, true));
 	}
 
 	renderElement(node: ITreeNode<OutlineGroup, FuzzyScore>, index: number, template: OutlineGroupTemplate): void {
@@ -109,7 +112,7 @@ export class OutlineElementRenderer implements ITreeRenderer<OutlineElement, Fuz
 		const iconLabel = new IconLabel(container, { supportHighlights: true });
 		const decoration = dom.$('.outline-element-decoration');
 		container.appendChild(decoration);
-		return { container, iconLabel, decoration };
+		return new OutlineElementTemplate(container, iconLabel, decoration);
 	}
 
 	renderElement(node: ITreeNode<OutlineElement, FuzzyScore>, index: number, template: OutlineElementTemplate): void {
diff --git a/src/vs/editor/contrib/goToDefinition/goToDefinitionMouse.ts b/src/vs/editor/contrib/goToDefinition/goToDefinitionMouse.ts
index 717c7ba4d13cbef14c4976704254ead3575b1402..7d0dd7ce4e1dd84cb841331c593701d32ce9ca6c 100644
--- a/src/vs/editor/contrib/goToDefinition/goToDefinitionMouse.ts
+++ b/src/vs/editor/contrib/goToDefinition/goToDefinitionMouse.ts
@@ -34,18 +34,16 @@ class GotoDefinitionWithMouseEditorContribution implements editorCommon.IEditorC
 
 	private readonly editor: ICodeEditor;
 	private readonly toUnhook = new DisposableStore();
-	private decorations: string[];
-	private currentWordUnderMouse: IWordAtPosition | null;
-	private previousPromise: CancelablePromise<LocationLink[] | null> | null;
+	private decorations: string[] = [];
+	private currentWordUnderMouse: IWordAtPosition | null = null;
+	private previousPromise: CancelablePromise<LocationLink[] | null> | null = null;
 
 	constructor(
 		editor: ICodeEditor,
 		@ITextModelService private readonly textModelResolverService: ITextModelService,
 		@IModeService private readonly modeService: IModeService
 	) {
-		this.decorations = [];
 		this.editor = editor;
-		this.previousPromise = null;
 
 		let linkGesture = new ClickLinkGesture(editor);
 		this.toUnhook.add(linkGesture);
diff --git a/src/vs/editor/contrib/referenceSearch/referencesModel.ts b/src/vs/editor/contrib/referenceSearch/referencesModel.ts
index 591092048d2f005245061d8034f2535bdd8a1711..35af7095f8b02b2f202cc68ddd061f596828abe3 100644
--- a/src/vs/editor/contrib/referenceSearch/referencesModel.ts
+++ b/src/vs/editor/contrib/referenceSearch/referencesModel.ts
@@ -89,7 +89,7 @@ export class FileReferences implements IDisposable {
 
 	private _children: OneReference[];
 	private _preview?: FilePreview;
-	private _resolved: boolean;
+	private _resolved?: boolean;
 	private _loadFailure: any;
 
 	constructor(private readonly _parent: ReferencesModel, private readonly _uri: URI) {
diff --git a/src/vs/editor/contrib/snippet/snippetParser.ts b/src/vs/editor/contrib/snippet/snippetParser.ts
index 46d069cddbc91b6c11b6d2a3cd7f94a2960349b6..69b0f621302ed96313b7045c09354044bdbdb822 100644
--- a/src/vs/editor/contrib/snippet/snippetParser.ts
+++ b/src/vs/editor/contrib/snippet/snippetParser.ts
@@ -56,12 +56,8 @@ export class Scanner {
 			|| (ch >= CharCode.A && ch <= CharCode.Z);
 	}
 
-	value: string;
-	pos: number;
-
-	constructor() {
-		this.text('');
-	}
+	value: string = '';
+	pos: number = 0;
 
 	text(value: string) {
 		this.value = value;
diff --git a/src/vs/editor/contrib/suggest/suggestAlternatives.ts b/src/vs/editor/contrib/suggest/suggestAlternatives.ts
index 4d480fa8f4f97d7758d27f3eb753146fc1e0ea85..e8a6ea1a33846feacece07d05ccc16d055eef7ed 100644
--- a/src/vs/editor/contrib/suggest/suggestAlternatives.ts
+++ b/src/vs/editor/contrib/suggest/suggestAlternatives.ts
@@ -15,7 +15,7 @@ export class SuggestAlternatives {
 
 	private readonly _ckOtherSuggestions: IContextKey<boolean>;
 
-	private _index: number;
+	private _index: number = 0;
 	private _model: CompletionModel | undefined;
 	private _acceptNext: ((selected: ISelectedSuggestion) => any) | undefined;
 	private _listener: IDisposable | undefined;
diff --git a/src/vs/editor/contrib/suggest/wordContextKey.ts b/src/vs/editor/contrib/suggest/wordContextKey.ts
index 9461b86d339d1117c8abbcec99232054a011e3f8..7ec28a4cbef7624b5ebd5521ff758856d7168912 100644
--- a/src/vs/editor/contrib/suggest/wordContextKey.ts
+++ b/src/vs/editor/contrib/suggest/wordContextKey.ts
@@ -13,7 +13,7 @@ export class WordContextKey extends Disposable {
 
 	private readonly _ckAtEnd: IContextKey<boolean>;
 
-	private _enabled: boolean;
+	private _enabled: boolean = false;
 	private _selectionListener?: IDisposable;
 
 	constructor(
diff --git a/src/vs/workbench/api/browser/mainThreadCodeInsets.ts b/src/vs/workbench/api/browser/mainThreadCodeInsets.ts
index 48938ad1f5b1d62e22a2c398fee1071efc9e6feb..1e23e14ce69ca5634ca0189820c8a9f0dccacc3a 100644
--- a/src/vs/workbench/api/browser/mainThreadCodeInsets.ts
+++ b/src/vs/workbench/api/browser/mainThreadCodeInsets.ts
@@ -21,7 +21,7 @@ class EditorWebviewZone implements IViewZone {
 	readonly afterColumn: number;
 	readonly heightInLines: number;
 
-	private _id: number;
+	private _id?: number;
 	// suppressMouseDown?: boolean | undefined;
 	// heightInPx?: number | undefined;
 	// minWidthInPx?: number | undefined;
@@ -46,7 +46,7 @@ class EditorWebviewZone implements IViewZone {
 	}
 
 	dispose(): void {
-		this.editor.changeViewZones(accessor => accessor.removeZone(this._id));
+		this.editor.changeViewZones(accessor => this._id && accessor.removeZone(this._id));
 	}
 }
 
diff --git a/src/vs/workbench/api/browser/mainThreadDocumentsAndEditors.ts b/src/vs/workbench/api/browser/mainThreadDocumentsAndEditors.ts
index 804349ee484e8081852393c55f8238b467b07b9b..10037f6c21a3c1764bbd8f1da8e1e3eb4ef7ed06 100644
--- a/src/vs/workbench/api/browser/mainThreadDocumentsAndEditors.ts
+++ b/src/vs/workbench/api/browser/mainThreadDocumentsAndEditors.ts
@@ -109,7 +109,7 @@ class DocumentAndEditorStateDelta {
 
 class DocumentAndEditorState {
 
-	static compute(before: DocumentAndEditorState, after: DocumentAndEditorState): DocumentAndEditorStateDelta {
+	static compute(before: DocumentAndEditorState | undefined, after: DocumentAndEditorState): DocumentAndEditorStateDelta {
 		if (!before) {
 			return new DocumentAndEditorStateDelta(
 				[], values(after.documents),
@@ -146,7 +146,7 @@ class MainThreadDocumentAndEditorStateComputer {
 
 	private readonly _toDispose = new DisposableStore();
 	private _toDisposeOnEditorRemove = new Map<string, IDisposable>();
-	private _currentState: DocumentAndEditorState;
+	private _currentState?: DocumentAndEditorState;
 	private _activeEditorOrder: ActiveEditorOrder = ActiveEditorOrder.Editor;
 
 	constructor(
diff --git a/src/vs/workbench/api/common/extHostCodeInsets.ts b/src/vs/workbench/api/common/extHostCodeInsets.ts
index cf7f22b692a3c5f22752c7eacfc51fd0e3debe62..066b25f2b026d96a5a39ed53e499afc0a1d87233 100644
--- a/src/vs/workbench/api/common/extHostCodeInsets.ts
+++ b/src/vs/workbench/api/common/extHostCodeInsets.ts
@@ -63,7 +63,7 @@ export class ExtHostEditorInsets implements ExtHostEditorInsetsShape {
 
 			private readonly _uuid = generateUuid();
 			private _html: string = '';
-			private _options: vscode.WebviewOptions;
+			private _options: vscode.WebviewOptions = Object.create(null);
 
 			toWebviewResource(resource: vscode.Uri): vscode.Uri {
 				return toWebviewResource(that._initData, this._uuid, resource);
diff --git a/src/vs/workbench/api/common/extHostDocumentData.ts b/src/vs/workbench/api/common/extHostDocumentData.ts
index 96f70218b48facebecc5718fa4889d12d9d6c65f..b44527a2b51e49edcbdb80f5fb40fc504555504e 100644
--- a/src/vs/workbench/api/common/extHostDocumentData.ts
+++ b/src/vs/workbench/api/common/extHostDocumentData.ts
@@ -26,7 +26,7 @@ export class ExtHostDocumentData extends MirrorTextModel {
 	private _proxy: MainThreadDocumentsShape;
 	private _languageId: string;
 	private _isDirty: boolean;
-	private _document: vscode.TextDocument;
+	private _document?: vscode.TextDocument;
 	private _textLines: vscode.TextLine[] = [];
 	private _isDisposed: boolean = false;
 
diff --git a/src/vs/workbench/api/common/extHostDocumentsAndEditors.ts b/src/vs/workbench/api/common/extHostDocumentsAndEditors.ts
index 5157bb712674b8de2516c2664f809446c1a3345a..98002f78c717159646bcffda699419f0f3824f49 100644
--- a/src/vs/workbench/api/common/extHostDocumentsAndEditors.ts
+++ b/src/vs/workbench/api/common/extHostDocumentsAndEditors.ts
@@ -17,7 +17,7 @@ export class ExtHostDocumentsAndEditors implements ExtHostDocumentsAndEditorsSha
 
 	private _disposables: Disposable[] = [];
 
-	private _activeEditorId: string | null;
+	private _activeEditorId: string | null = null;
 
 	private readonly _editors = new Map<string, ExtHostTextEditor>();
 	private readonly _documents = new Map<string, ExtHostDocumentData>();
diff --git a/src/vs/workbench/api/common/extHostFileSystem.ts b/src/vs/workbench/api/common/extHostFileSystem.ts
index 9f0519b636f04e2ae5c514478890b9b553ca71ed..4b82d98426b7fa51dc61f7f7d2c3b5a668a2e34b 100644
--- a/src/vs/workbench/api/common/extHostFileSystem.ts
+++ b/src/vs/workbench/api/common/extHostFileSystem.ts
@@ -155,7 +155,7 @@ export class ExtHostFileSystem implements ExtHostFileSystemShape {
 	private readonly _usedSchemes = new Set<string>();
 	private readonly _watches = new Map<number, IDisposable>();
 
-	private _linkProviderRegistration: IDisposable;
+	private _linkProviderRegistration?: IDisposable;
 	private _handlePool: number = 0;
 
 	readonly fileSystem: vscode.FileSystem;
diff --git a/src/vs/workbench/api/common/extHostMemento.ts b/src/vs/workbench/api/common/extHostMemento.ts
index 4502bacd67120bb6462f0a63431c69044d7fb282..d0e68010a17ca88d487bd1dd50310dc9f7902cff 100644
--- a/src/vs/workbench/api/common/extHostMemento.ts
+++ b/src/vs/workbench/api/common/extHostMemento.ts
@@ -14,7 +14,7 @@ export class ExtensionMemento implements IExtensionMemento {
 	private readonly _storage: ExtHostStorage;
 
 	private readonly _init: Promise<ExtensionMemento>;
-	private _value: { [n: string]: any; };
+	private _value?: { [n: string]: any; };
 	private readonly _storageListener: IDisposable;
 
 	constructor(id: string, global: boolean, storage: ExtHostStorage) {
@@ -41,7 +41,7 @@ export class ExtensionMemento implements IExtensionMemento {
 	get<T>(key: string): T | undefined;
 	get<T>(key: string, defaultValue: T): T;
 	get<T>(key: string, defaultValue?: T): T {
-		let value = this._value[key];
+		let value = this._value![key];
 		if (typeof value === 'undefined') {
 			value = defaultValue;
 		}
@@ -49,8 +49,8 @@ export class ExtensionMemento implements IExtensionMemento {
 	}
 
 	update(key: string, value: any): Promise<void> {
-		this._value[key] = value;
-		return this._storage.setValue(this._shared, this._id, this._value);
+		this._value![key] = value;
+		return this._storage.setValue(this._shared, this._id, this._value!);
 	}
 
 	dispose(): void {
diff --git a/src/vs/workbench/api/common/extHostOutput.ts b/src/vs/workbench/api/common/extHostOutput.ts
index 09ae3c549fc06622b67bbf91739de36fc360ab21..3580d0e6679c057b4b03f3a3118765a63c6a9475 100644
--- a/src/vs/workbench/api/common/extHostOutput.ts
+++ b/src/vs/workbench/api/common/extHostOutput.ts
@@ -27,6 +27,7 @@ export abstract class AbstractExtHostOutputChannel extends Disposable implements
 		this._name = name;
 		this._proxy = proxy;
 		this._id = proxy.$register(this.name, log, file);
+		this._disposed = false;
 		this._offset = 0;
 	}
 
@@ -121,7 +122,7 @@ export class ExtHostOutputService implements ExtHostOutputServiceShape {
 	private readonly _logsLocation: URI;
 	private readonly _proxy: MainThreadOutputServiceShape;
 	private readonly _channels: Map<string, AbstractExtHostOutputChannel> = new Map<string, AbstractExtHostOutputChannel>();
-	private _visibleChannelDisposable: IDisposable;
+	private _visibleChannelDisposable?: IDisposable;
 
 	constructor(factory: IOutputChannelFactory, logsLocation: URI, mainContext: IMainContext) {
 		this._factory = factory;
diff --git a/src/vs/workbench/browser/parts/editor/breadcrumbs.ts b/src/vs/workbench/browser/parts/editor/breadcrumbs.ts
index ca8fb69dd8c1af184368712932ce558335e22eb1..85aed7a9bf40ee171d0e1475835805b9938aa0dd 100644
--- a/src/vs/workbench/browser/parts/editor/breadcrumbs.ts
+++ b/src/vs/workbench/browser/parts/editor/breadcrumbs.ts
@@ -29,7 +29,7 @@ export interface IBreadcrumbsService {
 
 export class BreadcrumbsService implements IBreadcrumbsService {
 
-	_serviceBrand: ServiceIdentifier<any>;
+	_serviceBrand: any;
 
 	private readonly _map = new Map<number, BreadcrumbsWidget>();
 
@@ -55,8 +55,8 @@ registerSingleton(IBreadcrumbsService, BreadcrumbsService, true);
 
 export abstract class BreadcrumbsConfig<T> {
 
-	name: string;
-	onDidChange: Event<void>;
+	abstract get name(): string;
+	abstract get onDidChange(): Event<void>;
 
 	abstract getValue(overrides?: IConfigurationOverrides): T;
 	abstract updateValue(value: T, overrides?: IConfigurationOverrides): Promise<void>;
diff --git a/src/vs/workbench/contrib/extensions/electron-browser/extensionProfileService.ts b/src/vs/workbench/contrib/extensions/electron-browser/extensionProfileService.ts
index 283c3406d8f4cc4bede50c8844b967c0913330ab..af073fb2c6f7803f5ad9d970c88b75c15ce577cc 100644
--- a/src/vs/workbench/contrib/extensions/electron-browser/extensionProfileService.ts
+++ b/src/vs/workbench/contrib/extensions/electron-browser/extensionProfileService.ts
@@ -5,7 +5,7 @@
 
 import * as nls from 'vs/nls';
 import { Event, Emitter } from 'vs/base/common/event';
-import { IInstantiationService, ServiceIdentifier } from 'vs/platform/instantiation/common/instantiation';
+import { IInstantiationService } from 'vs/platform/instantiation/common/instantiation';
 import { IExtensionHostProfile, ProfileSession, IExtensionService } from 'vs/workbench/services/extensions/common/extensions';
 import { Disposable, toDisposable, MutableDisposable } from 'vs/base/common/lifecycle';
 import { onUnexpectedError } from 'vs/base/common/errors';
@@ -23,7 +23,7 @@ import { CommandsRegistry } from 'vs/platform/commands/common/commands';
 
 export class ExtensionHostProfileService extends Disposable implements IExtensionHostProfileService {
 
-	_serviceBrand: ServiceIdentifier<IExtensionHostProfileService>;
+	_serviceBrand: any;
 
 	private readonly _onDidChangeState: Emitter<void> = this._register(new Emitter<void>());
 	public readonly onDidChangeState: Event<void> = this._onDidChangeState.event;
@@ -34,7 +34,7 @@ export class ExtensionHostProfileService extends Disposable implements IExtensio
 	private readonly _unresponsiveProfiles = new Map<string, IExtensionHostProfile>();
 	private _profile: IExtensionHostProfile | null;
 	private _profileSession: ProfileSession | null;
-	private _state: ProfileSessionState;
+	private _state: ProfileSessionState = ProfileSessionState.None;
 
 	private profilingStatusBarIndicator: IStatusbarEntryAccessor | undefined;
 	private readonly profilingStatusBarIndicatorLabelUpdater = this._register(new MutableDisposable());
diff --git a/src/vs/workbench/contrib/extensions/electron-browser/extensionsSlowActions.ts b/src/vs/workbench/contrib/extensions/electron-browser/extensionsSlowActions.ts
index 3b81b03291c536a2f27627cdbdd56c1e6e8fd251..11aacd0695543f127e503e822d898ac19ad4a96b 100644
--- a/src/vs/workbench/contrib/extensions/electron-browser/extensionsSlowActions.ts
+++ b/src/vs/workbench/contrib/extensions/electron-browser/extensionsSlowActions.ts
@@ -19,9 +19,9 @@ import { IDialogService } from 'vs/platform/dialogs/common/dialogs';
 import Severity from 'vs/base/common/severity';
 
 abstract class RepoInfo {
-	readonly base: string;
-	readonly owner: string;
-	readonly repo: string;
+	abstract get base(): string;
+	abstract get owner(): string;
+	abstract get repo(): string;
 
 	static fromExtension(desc: IExtensionDescription): RepoInfo | undefined {
 
diff --git a/src/vs/workbench/contrib/markers/browser/markersFileDecorations.ts b/src/vs/workbench/contrib/markers/browser/markersFileDecorations.ts
index ce1755e1f0932cbb76ba5ca190f6e3a76a15cebe..7c13cb5575efe6d70f0df35102001507d1b1102e 100644
--- a/src/vs/workbench/contrib/markers/browser/markersFileDecorations.ts
+++ b/src/vs/workbench/contrib/markers/browser/markersFileDecorations.ts
@@ -56,8 +56,8 @@ class MarkersDecorationsProvider implements IDecorationsProvider {
 class MarkersFileDecorations implements IWorkbenchContribution {
 
 	private readonly _disposables: IDisposable[];
-	private _provider: IDisposable;
-	private _enabled: boolean;
+	private _provider?: IDisposable;
+	private _enabled?: boolean;
 
 	constructor(
 		@IMarkerService private readonly _markerService: IMarkerService,
diff --git a/src/vs/workbench/contrib/performance/electron-browser/perfviewEditor.ts b/src/vs/workbench/contrib/performance/electron-browser/perfviewEditor.ts
index 052e4bd2f5c7dada12b496dd57f9347e1781e737..f0f73e07083f66e36c3570b45eab4ef310bd1d24 100644
--- a/src/vs/workbench/contrib/performance/electron-browser/perfviewEditor.ts
+++ b/src/vs/workbench/contrib/performance/electron-browser/perfviewEditor.ts
@@ -262,11 +262,11 @@ class PerfModelContentProvider implements ITextModelContentProvider {
 }
 
 abstract class LoaderStats {
-	readonly amdLoad: (string | number)[][];
-	readonly amdInvoke: (string | number)[][];
-	readonly nodeRequire: (string | number)[][];
-	readonly nodeEval: (string | number)[][];
-	readonly nodeRequireTotal: number;
+	abstract get amdLoad(): (string | number)[][];
+	abstract get amdInvoke(): (string | number)[][];
+	abstract get nodeRequire(): (string | number)[][];
+	abstract get nodeEval(): (string | number)[][];
+	abstract get nodeRequireTotal(): number;
 
 
 	static get(): LoaderStats {
diff --git a/src/vs/workbench/contrib/snippets/browser/snippetCompletionProvider.ts b/src/vs/workbench/contrib/snippets/browser/snippetCompletionProvider.ts
index ec5d1ce087b3596de34d59dd9d4102f09286a92f..54888ea75b7f515add3fa8bfd271ae46539c816b 100644
--- a/src/vs/workbench/contrib/snippets/browser/snippetCompletionProvider.ts
+++ b/src/vs/workbench/contrib/snippets/browser/snippetCompletionProvider.ts
@@ -21,7 +21,7 @@ export class SnippetCompletion implements CompletionItem {
 	label: string;
 	detail: string;
 	insertText: string;
-	documentation: MarkdownString;
+	documentation?: MarkdownString;
 	range: IRange;
 	sortText: string;
 	kind: CompletionItemKind;
diff --git a/src/vs/workbench/contrib/snippets/browser/tabCompletion.ts b/src/vs/workbench/contrib/snippets/browser/tabCompletion.ts
index 8154a9da36498c5dba5d78ec3db7c985bdbd3b31..569598138e8e380b7b0cf65f39463d5f3ead99a7 100644
--- a/src/vs/workbench/contrib/snippets/browser/tabCompletion.ts
+++ b/src/vs/workbench/contrib/snippets/browser/tabCompletion.ts
@@ -31,8 +31,8 @@ export class TabCompletionController implements editorCommon.IEditorContribution
 
 	private _hasSnippets: IContextKey<boolean>;
 	private _activeSnippets: Snippet[] = [];
-	private _enabled: boolean;
-	private _selectionListener: IDisposable;
+	private _enabled?: boolean;
+	private _selectionListener?: IDisposable;
 	private readonly _configListener: IDisposable;
 
 	constructor(
diff --git a/src/vs/workbench/contrib/splash/electron-browser/partsSplash.contribution.ts b/src/vs/workbench/contrib/splash/electron-browser/partsSplash.contribution.ts
index 179c565335d94a40b5f3f80cbc80e2fc3300823d..011b14816fb79ae6a6c2c7ce40246857ff05d671 100644
--- a/src/vs/workbench/contrib/splash/electron-browser/partsSplash.contribution.ts
+++ b/src/vs/workbench/contrib/splash/electron-browser/partsSplash.contribution.ts
@@ -32,8 +32,8 @@ class PartsSplash {
 
 	private readonly _disposables = new DisposableStore();
 
-	private _didChangeTitleBarStyle: boolean;
-	private _lastBaseTheme: string;
+	private _didChangeTitleBarStyle?: boolean;
+	private _lastBaseTheme?: string;
 	private _lastBackground?: string;
 
 	constructor(
diff --git a/src/vs/workbench/services/bulkEdit/browser/bulkEditService.ts b/src/vs/workbench/services/bulkEdit/browser/bulkEditService.ts
index f698782a600bfa704a80717135f69ba16ecd90c5..fff264d6463f0864beca40d9a4979be510535a6b 100644
--- a/src/vs/workbench/services/bulkEdit/browser/bulkEditService.ts
+++ b/src/vs/workbench/services/bulkEdit/browser/bulkEditService.ts
@@ -51,7 +51,7 @@ class ModelEditTask implements IDisposable {
 
 	protected _edits: IIdentifiedSingleEditOperation[];
 	private _expectedModelVersionId: number | undefined;
-	protected _newEol: EndOfLineSequence;
+	protected _newEol: EndOfLineSequence | undefined;
 
 	constructor(private readonly _modelReference: IReference<IResolvedTextEditorModel>) {
 		this._model = this._modelReference.object.textEditorModel;
@@ -142,7 +142,7 @@ class BulkEditModel implements IDisposable {
 	private _textModelResolverService: ITextModelService;
 	private _edits = new Map<string, ResourceTextEdit[]>();
 	private _editor: ICodeEditor | undefined;
-	private _tasks: ModelEditTask[];
+	private _tasks: ModelEditTask[] | undefined;
 	private _progress: IProgress<void>;
 
 	constructor(
@@ -159,7 +159,7 @@ class BulkEditModel implements IDisposable {
 	}
 
 	dispose(): void {
-		this._tasks = dispose(this._tasks);
+		this._tasks = dispose(this._tasks!);
 	}
 
 	addEdit(edit: ResourceTextEdit): void {
@@ -196,7 +196,7 @@ class BulkEditModel implements IDisposable {
 				}
 
 				value.forEach(edit => task.addEdit(edit));
-				this._tasks.push(task);
+				this._tasks!.push(task);
 				this._progress.report(undefined);
 			});
 			promises.push(promise);
@@ -208,7 +208,7 @@ class BulkEditModel implements IDisposable {
 	}
 
 	validate(): ValidationResult {
-		for (const task of this._tasks) {
+		for (const task of this._tasks!) {
 			const result = task.validate();
 			if (!result.canApply) {
 				return result;
@@ -218,7 +218,7 @@ class BulkEditModel implements IDisposable {
 	}
 
 	apply(): void {
-		for (const task of this._tasks) {
+		for (const task of this._tasks!) {
 			task.apply();
 			this._progress.report(undefined);
 		}
diff --git a/src/vs/workbench/services/timer/electron-browser/timerService.ts b/src/vs/workbench/services/timer/electron-browser/timerService.ts
index ffc0854905f98b1468e9df1de23dfad9f33023fe..45d1e342b7691ae2cd130d0df2e91d7c4391dc4d 100644
--- a/src/vs/workbench/services/timer/electron-browser/timerService.ts
+++ b/src/vs/workbench/services/timer/electron-browser/timerService.ts
@@ -305,7 +305,7 @@ class TimerService implements ITimerService {
 
 	_serviceBrand: any;
 
-	private _startupMetrics: Promise<IStartupMetrics>;
+	private _startupMetrics?: Promise<IStartupMetrics>;
 
 	constructor(
 		@IWindowsService private readonly _windowsService: IWindowsService,