diff --git a/src/vs/workbench/api/common/extHostQuickOpen.ts b/src/vs/workbench/api/common/extHostQuickOpen.ts
index c8587620994a7bee97166ea485c1451fa2c0f95f..65f94310001952c094b23ec8fc3685703c7d7cd0 100644
--- a/src/vs/workbench/api/common/extHostQuickOpen.ts
+++ b/src/vs/workbench/api/common/extHostQuickOpen.ts
@@ -234,16 +234,16 @@ class ExtHostQuickInput implements QuickInput {
 	private static _nextId = 1;
 	_id = ExtHostQuickPick._nextId++;
 
-	private _title: string;
-	private _steps: number;
-	private _totalSteps: number;
+	private _title: string | undefined;
+	private _steps: number | undefined;
+	private _totalSteps: number | undefined;
 	private _visible = false;
 	private _expectingHide = false;
 	private _enabled = true;
 	private _busy = false;
 	private _ignoreFocusOut = true;
 	private _value = '';
-	private _placeholder: string;
+	private _placeholder: string | undefined;
 	private _buttons: QuickInputButton[] = [];
 	private _handlesToButtons = new Map<number, QuickInputButton>();
 	private readonly _onDidAcceptEmitter = new Emitter<void>();
@@ -268,7 +268,7 @@ class ExtHostQuickInput implements QuickInput {
 		return this._title;
 	}
 
-	set title(title: string) {
+	set title(title: string | undefined) {
 		this._title = title;
 		this.update({ title });
 	}
@@ -277,7 +277,7 @@ class ExtHostQuickInput implements QuickInput {
 		return this._steps;
 	}
 
-	set step(step: number) {
+	set step(step: number | undefined) {
 		this._steps = step;
 		this.update({ step });
 	}
@@ -286,7 +286,7 @@ class ExtHostQuickInput implements QuickInput {
 		return this._totalSteps;
 	}
 
-	set totalSteps(totalSteps: number) {
+	set totalSteps(totalSteps: number | undefined) {
 		this._totalSteps = totalSteps;
 		this.update({ totalSteps });
 	}
@@ -331,7 +331,7 @@ class ExtHostQuickInput implements QuickInput {
 		return this._placeholder;
 	}
 
-	set placeholder(placeholder: string) {
+	set placeholder(placeholder: string | undefined) {
 		this._placeholder = placeholder;
 		this.update({ placeholder });
 	}
@@ -398,7 +398,7 @@ class ExtHostQuickInput implements QuickInput {
 		}
 	}
 
-	public dispose(): void {
+	dispose(): void {
 		if (this._disposed) {
 			return;
 		}
@@ -587,9 +587,9 @@ class ExtHostQuickPick<T extends QuickPickItem> extends ExtHostQuickInput implem
 
 class ExtHostInputBox extends ExtHostQuickInput implements InputBox {
 
-	private _password: boolean;
-	private _prompt: string;
-	private _validationMessage: string;
+	private _password = false;
+	private _prompt: string | undefined;
+	private _validationMessage: string | undefined;
 
 	constructor(proxy: MainThreadQuickOpenShape, extensionId: ExtensionIdentifier, onDispose: () => void) {
 		super(proxy, extensionId, onDispose);
@@ -609,7 +609,7 @@ class ExtHostInputBox extends ExtHostQuickInput implements InputBox {
 		return this._prompt;
 	}
 
-	set prompt(prompt: string) {
+	set prompt(prompt: string | undefined) {
 		this._prompt = prompt;
 		this.update({ prompt });
 	}
@@ -618,7 +618,7 @@ class ExtHostInputBox extends ExtHostQuickInput implements InputBox {
 		return this._validationMessage;
 	}
 
-	set validationMessage(validationMessage: string) {
+	set validationMessage(validationMessage: string | undefined) {
 		this._validationMessage = validationMessage;
 		this.update({ validationMessage });
 	}
diff --git a/src/vs/workbench/services/configuration/browser/configurationService.ts b/src/vs/workbench/services/configuration/browser/configurationService.ts
index 5df245052bf5d919efb1ce0aceb84679cad6476f..168076becf7952eb2fa1bfcb85de148e6cddc6e2 100644
--- a/src/vs/workbench/services/configuration/browser/configurationService.ts
+++ b/src/vs/workbench/services/configuration/browser/configurationService.ts
@@ -59,10 +59,10 @@ export class WorkspaceService extends Disposable implements IConfigurationServic
 	protected readonly _onDidChangeWorkbenchState: Emitter<WorkbenchState> = this._register(new Emitter<WorkbenchState>());
 	public readonly onDidChangeWorkbenchState: Event<WorkbenchState> = this._onDidChangeWorkbenchState.event;
 
-	private configurationEditingService: ConfigurationEditingService;
-	private jsonEditingService: JSONEditingService;
-
-	private cyclicDependencyReady: Function;
+	// TODO@sandeep debt with cyclic dependencies
+	private configurationEditingService!: ConfigurationEditingService;
+	private jsonEditingService!: JSONEditingService;
+	private cyclicDependencyReady!: Function;
 	private cyclicDependency = new Promise<void>(resolve => this.cyclicDependencyReady = resolve);
 
 	constructor(
diff --git a/src/vs/workbench/services/preferences/common/preferencesModels.ts b/src/vs/workbench/services/preferences/common/preferencesModels.ts
index 61be470078619f1f0aeacd068e046c6cf1a7e602..59dcd697acf21e219d2ae001d4d93ce2cd5f6527 100644
--- a/src/vs/workbench/services/preferences/common/preferencesModels.ts
+++ b/src/vs/workbench/services/preferences/common/preferencesModels.ts
@@ -429,7 +429,7 @@ function parse(model: ITextModel, isSettingsProperty: (currentProperty: string,
 
 export class WorkspaceConfigurationEditorModel extends SettingsEditorModel {
 
-	private _configurationGroups: ISettingsGroup[];
+	private _configurationGroups: ISettingsGroup[] = [];
 
 	get configurationGroups(): ISettingsGroup[] {
 		return this._configurationGroups;
@@ -448,9 +448,9 @@ export class WorkspaceConfigurationEditorModel extends SettingsEditorModel {
 
 export class DefaultSettings extends Disposable {
 
-	private _allSettingsGroups: ISettingsGroup[];
-	private _content: string;
-	private _settingsByName: Map<string, ISetting>;
+	private _allSettingsGroups: ISettingsGroup[] | undefined;
+	private _content: string | undefined;
+	private _settingsByName = new Map<string, ISetting>();
 
 	readonly _onDidChange: Emitter<void> = this._register(new Emitter<void>());
 	readonly onDidChange: Event<void> = this._onDidChange.event;
@@ -467,7 +467,7 @@ export class DefaultSettings extends Disposable {
 			this.initialize();
 		}
 
-		return this._content;
+		return this._content!;
 	}
 
 	getSettingsGroups(forceUpdate = false): ISettingsGroup[] {
@@ -475,7 +475,7 @@ export class DefaultSettings extends Disposable {
 			this.initialize();
 		}
 
-		return this._allSettingsGroups;
+		return this._allSettingsGroups!;
 	}
 
 	private initialize(): void {