Use undefined instead of null in $ dom creation methods

src/vs/workbench/contrib/preferences/browser/keybindingWidgets.ts

@@ -224,7 +224,7 @@ export class DefineKeybindingWidget extends Widget {
 		this._domNode.setHeight(DefineKeybindingWidget.HEIGHT);
 
 		const message = nls.localize('defineKeybinding.initial', "Press desired key combination and then press ENTER.");
-		dom.append(this._domNode.domNode, dom.$('.message', null, message));
+		dom.append(this._domNode.domNode, dom.$('.message', undefined, message));
 
 		this._register(attachStylerCallback(this.themeService, { editorWidgetBackground, widgetShadow }, colors => {
 			if (colors.editorWidgetBackground) {

src/vs/workbench/contrib/preferences/browser/keybindingsEditor.ts

@@ -364,8 +364,8 @@ export class KeybindingsEditor extends BaseEditor implements IKeybindingsEditor
 
 	private createOpenKeybindingsElement(parent: HTMLElement): void {
 		const openKeybindingsContainer = DOM.append(parent, $('.open-keybindings-container'));
-		DOM.append(openKeybindingsContainer, $('', null, localize('header-message', "For advanced customizations open and edit")));
-		const fileElement = DOM.append(openKeybindingsContainer, $('.file-name', null, localize('keybindings-file-name', "keybindings.json")));
+		DOM.append(openKeybindingsContainer, $('', undefined, localize('header-message', "For advanced customizations open and edit")));
+		const fileElement = DOM.append(openKeybindingsContainer, $('.file-name', undefined, localize('keybindings-file-name', "keybindings.json")));
 		fileElement.tabIndex = 0;
 		this._register(DOM.addDisposableListener(fileElement, DOM.EventType.CLICK, () => this.preferencesService.openGlobalKeybindingSettings(true)));
 		this._register(DOM.addDisposableListener(fileElement, DOM.EventType.KEY_UP, e => {
@@ -398,10 +398,10 @@ export class KeybindingsEditor extends BaseEditor implements IKeybindingsEditor
 		keybindingsListHeader.style.lineHeight = '30px';
 		DOM.append(keybindingsListHeader,
 			$('.header.actions'),
-			$('.header.command', null, localize('command', "Command")),
-			$('.header.keybinding', null, localize('keybinding', "Keybinding")),
-			$('.header.source', null, localize('source', "Source")),
-			$('.header.when', null, localize('when', "When")));
+			$('.header.command', undefined, localize('command', "Command")),
+			$('.header.keybinding', undefined, localize('keybinding', "Keybinding")),
+			$('.header.source', undefined, localize('source', "Source")),
+			$('.header.when', undefined, localize('when', "When")));
 	}
 
 	private createList(parent: HTMLElement): void {

src/vs/workbench/contrib/preferences/browser/settingsTree.ts

@@ -252,7 +252,7 @@ export interface ISettingOverrideClickEvent {
 
 export abstract class AbstractSettingRenderer implements ITreeRenderer<SettingsTreeElement, never, any> {
 	/** To override */
-	templateId = undefined;
+	abstract get templateId(): string;
 
 	static readonly CONTROL_CLASS = 'setting-control-focus-target';
 	static readonly CONTROL_SELECTOR = '.' + AbstractSettingRenderer.CONTROL_CLASS;
@@ -418,15 +418,15 @@ export abstract class AbstractSettingRenderer implements ITreeRenderer<SettingsT
 				localize('alsoConfiguredIn', "Also modified in") :
 				localize('configuredIn', "Modified in");
 
-			DOM.append(template.otherOverridesElement, $('span', null, `(${otherOverridesLabel}: `));
+			DOM.append(template.otherOverridesElement, $('span', undefined, `(${otherOverridesLabel}: `));
 
 			for (let i = 0; i < element.overriddenScopeList.length; i++) {
-				const view = DOM.append(template.otherOverridesElement, $('a.modified-scope', null, element.overriddenScopeList[i]));
+				const view = DOM.append(template.otherOverridesElement, $('a.modified-scope', undefined, element.overriddenScopeList[i]));
 
 				if (i !== element.overriddenScopeList.length - 1) {
-					DOM.append(template.otherOverridesElement, $('span', null, ', '));
+					DOM.append(template.otherOverridesElement, $('span', undefined, ', '));
 				} else {
-					DOM.append(template.otherOverridesElement, $('span', null, ')'));
+					DOM.append(template.otherOverridesElement, $('span', undefined, ')'));
 				}
 
 				DOM.addStandardDisposableListener(view, DOM.EventType.CLICK, (e: IMouseEvent) => {

src/vs/workbench/contrib/scm/electron-browser/scmViewlet.ts

@@ -782,7 +782,7 @@ export class RepositoryPanel extends ViewletPanel {
 
 		super.renderHeaderTitle(container, title);
 		addClass(container, 'scm-provider');
-		append(container, $('span.type', null, type));
+		append(container, $('span.type', undefined, type));
 		const onContextMenu = Event.map(stop(domEvent(container, 'contextmenu')), e => new StandardMouseEvent(e));
 		onContextMenu(this.onContextMenu, this, this.disposables);
 	}
@@ -1097,7 +1097,7 @@ export class SCMViewlet extends PanelViewlet implements IViewModel, IViewsViewle
 		this.el = parent;
 		addClass(this.el, 'scm-viewlet');
 		addClass(this.el, 'empty');
-		append(parent, $('div.empty-message', null, localize('no open repo', "No source control providers registered.")));
+		append(parent, $('div.empty-message', undefined, localize('no open repo', "No source control providers registered.")));
 
 		this.scmService.onDidAddRepository(this.onDidAddRepository, this, this.disposables);
 		this.scmService.onDidRemoveRepository(this.onDidRemoveRepository, this, this.disposables);