Replace some instances of `|| null` with `withUndefinedAsNull`

The latter is more explicit, correctly handles some edge cases, and helps tag places in the code where we should look into replacing null with undefined.

src/vs/code/electron-browser/issue/issueReporterMain.ts

@@ -39,6 +39,7 @@ import { ILogService, getLogLevel } from 'vs/platform/log/common/log';
 import { OcticonLabel } from 'vs/base/browser/ui/octiconLabel/octiconLabel';
 import { normalizeGitHubUrl } from 'vs/code/electron-browser/issue/issueReporterUtil';
 import { Button } from 'vs/base/browser/ui/button/button';
+import { withUndefinedAsNull } from 'vs/base/common/types';
 
 const MAX_URL_LENGTH = platform.isWindows ? 2081 : 5400;
 
@@ -211,7 +212,7 @@ export class IssueReporter extends Disposable {
 
 		styleTag.innerHTML = content.join('\n');
 		document.head.appendChild(styleTag);
-		document.body.style.color = styles.color || null;
+		document.body.style.color = withUndefinedAsNull(styles.color);
 	}
 
 	private handleExtensionData(extensions: IssueReporterExtensionData[]) {

src/vs/editor/browser/editorExtensions.ts

@@ -20,6 +20,7 @@ import { IConstructorSignature1, ServicesAccessor } from 'vs/platform/instantiat
 import { IKeybindings, KeybindingsRegistry } from 'vs/platform/keybinding/common/keybindingsRegistry';
 import { Registry } from 'vs/platform/registry/common/platform';
 import { ITelemetryService } from 'vs/platform/telemetry/common/telemetry';
+import { withUndefinedAsNull } from 'vs/base/common/types';
 
 export type ServicesAccessor = ServicesAccessor;
 export type IEditorContributionCtor = IConstructorSignature1<ICodeEditor, IEditorContribution>;
@@ -88,7 +89,7 @@ export abstract class Command {
 				id: this.id,
 				handler: (accessor, args) => this.runCommand(accessor, args),
 				weight: this._kbOpts.weight,
-				when: kbWhen || null,
+				when: withUndefinedAsNull(kbWhen),
 				primary: this._kbOpts.primary,
 				secondary: this._kbOpts.secondary,
 				win: this._kbOpts.win,

src/vs/editor/common/services/languagesRegistry.ts

@@ -15,6 +15,7 @@ import { NULL_LANGUAGE_IDENTIFIER, NULL_MODE_ID } from 'vs/editor/common/modes/n
 import { ILanguageExtensionPoint } from 'vs/editor/common/services/modeService';
 import { Extensions, IConfigurationRegistry } from 'vs/platform/configuration/common/configurationRegistry';
 import { Registry } from 'vs/platform/registry/common/platform';
+import { withUndefinedAsNull } from 'vs/base/common/types';
 
 const hasOwnProperty = Object.prototype.hasOwnProperty;
 
@@ -267,7 +268,7 @@ export class LanguagesRegistry extends Disposable {
 			return null;
 		}
 		const language = this._languages[modeId];
-		return (language.mimetypes[0] || null);
+		return withUndefinedAsNull(language.mimetypes[0]);
 	}
 
 	public extractModeIds(commaSeparatedMimetypesOrCommaSeparatedIds: string | undefined): string[] {

src/vs/editor/common/services/markerDecorationsServiceImpl.ts

@@ -16,6 +16,7 @@ import { keys } from 'vs/base/common/map';
 import { IMarkerDecorationsService } from 'vs/editor/common/services/markersDecorationService';
 import { Schemas } from 'vs/base/common/network';
 import { Emitter, Event } from 'vs/base/common/event';
+import { withUndefinedAsNull } from 'vs/base/common/types';
 
 function MODEL_ID(resource: URI): string {
 	return resource.toString();
@@ -80,7 +81,7 @@ export class MarkerDecorationsService extends Disposable implements IMarkerDecor
 
 	getMarker(model: ITextModel, decoration: IModelDecoration): IMarker | null {
 		const markerDecorations = this._markerDecorations.get(MODEL_ID(model.uri));
-		return markerDecorations ? markerDecorations.getMarker(decoration) || null : null;
+		return markerDecorations ? withUndefinedAsNull(markerDecorations.getMarker(decoration)) : null;
 	}
 
 	getLiveMarkers(model: ITextModel): [Range, IMarker][] {

src/vs/platform/actions/common/menuService.ts

@@ -8,6 +8,7 @@ import { dispose, IDisposable } from 'vs/base/common/lifecycle';
 import { IMenu, IMenuActionOptions, IMenuItem, IMenuService, isIMenuItem, ISubmenuItem, MenuId, MenuItemAction, MenuRegistry, SubmenuItemAction } from 'vs/platform/actions/common/actions';
 import { ICommandService } from 'vs/platform/commands/common/commands';
 import { ContextKeyExpr, IContextKeyService } from 'vs/platform/contextkey/common/contextkey';
+import { withUndefinedAsNull } from 'vs/base/common/types';
 
 export class MenuService implements IMenuService {
 
@@ -110,7 +111,7 @@ class Menu implements IMenu {
 			const [id, items] = group;
 			const activeActions: Array<MenuItemAction | SubmenuItemAction> = [];
 			for (const item of items) {
-				if (this._contextKeyService.contextMatchesRules(item.when || null)) {
+				if (this._contextKeyService.contextMatchesRules(withUndefinedAsNull(item.when))) {
 					const action = isIMenuItem(item) ? new MenuItemAction(item.command, item.alt, options, this._contextKeyService, this._commandService) : new SubmenuItemAction(item);
 					activeActions.push(action);
 				}

src/vs/platform/configuration/common/configurationModels.ts

@@ -453,7 +453,7 @@ export class Configuration {
 		if (workspace && resource) {
 			const root = workspace.getFolder(resource);
 			if (root) {
-				return this._folderConfigurations.get(root.uri) || null;
+				return types.withUndefinedAsNull(this._folderConfigurations.get(root.uri));
 			}
 		}
 		return null;

src/vs/workbench/browser/parts/panel/panelPart.ts

@@ -30,7 +30,7 @@ import { Dimension, trackFocus } from 'vs/base/browser/dom';
 import { localize } from 'vs/nls';
 import { IDisposable } from 'vs/base/common/lifecycle';
 import { IContextKey, IContextKeyService } from 'vs/platform/contextkey/common/contextkey';
-import { isUndefinedOrNull } from 'vs/base/common/types';
+import { isUndefinedOrNull, withUndefinedAsNull } from 'vs/base/common/types';
 import { ILifecycleService, LifecyclePhase } from 'vs/platform/lifecycle/common/lifecycle';
 import { LayoutPriority } from 'vs/base/browser/ui/grid/gridview';
 import { registerSingleton } from 'vs/platform/instantiation/common/extensions';
@@ -222,7 +222,7 @@ export class PanelPart extends CompositePart<Panel> implements IPanelService {
 			}
 		}
 
-		return this.openComposite(id, focus) || null;
+		return withUndefinedAsNull(this.openComposite(id, focus));
 	}
 
 	showActivity(panelId: string, badge: IBadge, clazz?: string): IDisposable {

src/vs/workbench/browser/parts/quickopen/quickOpenController.ts

@@ -783,7 +783,7 @@ export class EditorHistoryEntry extends EditorQuickOpenEntry {
 	}
 
 	getResource(): URI | null {
-		return this.resource || null;
+		return types.withUndefinedAsNull(this.resource);
 	}
 
 	getInput(): IEditorInput | IResourceInput {

src/vs/workbench/common/editor/dataUriEditorInput.ts

@@ -8,6 +8,7 @@ import { URI } from 'vs/base/common/uri';
 import { IInstantiationService } from 'vs/platform/instantiation/common/instantiation';
 import { BinaryEditorModel } from 'vs/workbench/common/editor/binaryEditorModel';
 import { DataUri } from 'vs/base/common/resources';
+import { withUndefinedAsNull } from 'vs/base/common/types';
 
 /**
  * An editor input to present data URIs in a binary editor. Data URIs have the form of:
@@ -51,11 +52,11 @@ export class DataUriEditorInput extends EditorInput {
 	}
 
 	getName(): string | null {
-		return this.name || null;
+		return withUndefinedAsNull(this.name);
 	}
 
 	getDescription(): string | null {
-		return this.description || null;
+		return withUndefinedAsNull(this.description);
 	}
 
 	resolve(): Promise<BinaryEditorModel> {

src/vs/workbench/contrib/extensions/electron-browser/extensionEditor.ts

@@ -51,7 +51,7 @@ import { KeybindingParser } from 'vs/base/common/keybindingParser';
 import { IStorageService } from 'vs/platform/storage/common/storage';
 import { IExtensionService } from 'vs/workbench/services/extensions/common/extensions';
 import { getDefaultValue } from 'vs/platform/configuration/common/configurationRegistry';
-import { isUndefined } from 'vs/base/common/types';
+import { isUndefined, withUndefinedAsNull } from 'vs/base/common/types';
 import { IWorkbenchThemeService } from 'vs/workbench/services/themes/common/workbenchThemeService';
 
 function renderBody(body: string): string {
@@ -712,7 +712,7 @@ export class ExtensionEditor extends BaseEditor {
 
 			constructor(extension: IExtension, parent?: IExtensionData) {
 				this.extension = extension;
-				this.parent = parent || null;
+				this.parent = withUndefinedAsNull(parent);
 			}
 
 			get hasChildren(): boolean {

src/vs/workbench/contrib/markers/browser/markersModel.ts

@@ -12,6 +12,7 @@ import { values } from 'vs/base/common/map';
 import { memoize } from 'vs/base/common/decorators';
 import { Emitter, Event } from 'vs/base/common/event';
 import { Hasher } from 'vs/base/common/hash';
+import { withUndefinedAsNull } from 'vs/base/common/types';
 
 function compareUris(a: URI, b: URI) {
 	const astr = a.toString();
@@ -138,7 +139,7 @@ export class MarkersModel {
 	}
 
 	getResourceMarkers(resource: URI): ResourceMarkers | null {
-		return this.resourcesByUri.get(resource.toString()) || null;
+		return withUndefinedAsNull(this.resourcesByUri.get(resource.toString()));
 	}
 
 	setResourceMarkers(resource: URI, rawMarkers: IMarker[]): void {

src/vs/workbench/contrib/output/browser/outputServices.ts

@@ -27,6 +27,7 @@ import { ILifecycleService } from 'vs/platform/lifecycle/common/lifecycle';
 import { IContextKeyService } from 'vs/platform/contextkey/common/contextkey';
 import { CancellationToken } from 'vs/base/common/cancellation';
 import { IOutputChannelModel, IOutputChannelModelService } from 'vs/workbench/services/output/common/outputChannelModel';
+import { withUndefinedAsNull } from 'vs/base/common/types';
 
 const OUTPUT_ACTIVE_CHANNEL_KEY = 'output.activechannel';
 
@@ -141,7 +142,7 @@ export class OutputService extends Disposable implements IOutputService, ITextMo
 	}
 
 	getChannel(id: string): OutputChannel | null {
-		return this.channels.get(id) || null;
+		return withUndefinedAsNull(this.channels.get(id));
 	}
 
 	getChannelDescriptors(): IOutputChannelDescriptor[] {

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

@@ -4,7 +4,7 @@
  *--------------------------------------------------------------------------------------------*/
 
 import * as arrays from 'vs/base/common/arrays';
-import { isArray } from 'vs/base/common/types';
+import { isArray, withUndefinedAsNull } from 'vs/base/common/types';
 import { URI } from 'vs/base/common/uri';
 import { localize } from 'vs/nls';
 import { ConfigurationTarget, IConfigurationService } from 'vs/platform/configuration/common/configuration';
@@ -262,11 +262,11 @@ export class SettingsTreeModel {
 	}
 
 	getElementById(id: string): SettingsTreeElement | null {
-		return this._treeElementsById.get(id) || null;
+		return withUndefinedAsNull(this._treeElementsById.get(id));
 	}
 
 	getElementsByName(name: string): SettingsTreeSettingElement[] | null {
-		return this._treeElementsBySettingName.get(name) || null;
+		return withUndefinedAsNull(this._treeElementsBySettingName.get(name));
 	}
 
 	updateElementsByName(name: string): void {

src/vs/workbench/contrib/quickopen/browser/gotoLineHandler.ts

@@ -140,7 +140,7 @@ class GotoLineEntry extends EditorQuickOpenEntry {
 	}
 
 	getInput(): IEditorInput | null {
-		return this.editorService.activeEditor || null;
+		return types.withUndefinedAsNull(this.editorService.activeEditor);
 	}
 
 	getOptions(pinned?: boolean): ITextEditorOptions {

src/vs/workbench/contrib/quickopen/browser/gotoSymbolHandler.ts

@@ -289,7 +289,7 @@ class SymbolEntry extends EditorQuickOpenEntryGroup {
 	}
 
 	getInput(): IEditorInput | null {
-		return this.editorService.activeEditor || null;
+		return types.withUndefinedAsNull(this.editorService.activeEditor);
 	}
 
 	getOptions(pinned?: boolean): ITextEditorOptions {

src/vs/workbench/contrib/quickopen/browser/viewPickerHandler.ts

@@ -21,6 +21,7 @@ import { IContextKeyService } from 'vs/platform/contextkey/common/contextkey';
 import { ViewletDescriptor } from 'vs/workbench/browser/viewlet';
 import { Registry } from 'vs/platform/registry/common/platform';
 import { CancellationToken } from 'vs/base/common/cancellation';
+import { withUndefinedAsNull } from 'vs/base/common/types';
 
 export const VIEW_PICKER_PREFIX = 'view ';
 
@@ -137,7 +138,7 @@ export class ViewPickerHandler extends QuickOpenHandler {
 			const result: ViewEntry[] = [];
 			if (views.length) {
 				for (const view of views) {
-					if (this.contextKeyService.contextMatchesRules(view.when || null)) {
+					if (this.contextKeyService.contextMatchesRules(withUndefinedAsNull(view.when))) {
 						result.push(new ViewEntry(view.name, viewlet.name, () => this.viewsService.openView(view.id, true)));
 					}
 				}

src/vs/workbench/contrib/search/browser/openSymbolHandler.ts

@@ -25,6 +25,7 @@ import { ILabelService } from 'vs/platform/label/common/label';
 import { CancellationToken } from 'vs/base/common/cancellation';
 import { Schemas } from 'vs/base/common/network';
 import { IOpenerService } from 'vs/platform/opener/common/opener';
+import { withUndefinedAsNull } from 'vs/base/common/types';
 
 class SymbolEntry extends EditorQuickOpenEntry {
 	private bearingResolve: Promise<this | undefined>;
@@ -58,7 +59,7 @@ class SymbolEntry extends EditorQuickOpenEntry {
 			return this.labelService.getUriLabel(this.bearing.location.uri, { relative: true });
 		}
 
-		return containerName || null;
+		return withUndefinedAsNull(containerName);
 	}
 
 	getIcon(): string {

src/vs/workbench/services/configuration/common/configurationEditingService.ts

@@ -27,6 +27,7 @@ import { IEditorService } from 'vs/workbench/services/editor/common/editorServic
 import { ITextModel } from 'vs/editor/common/model';
 import { INotificationService, Severity } from 'vs/platform/notification/common/notification';
 import { IPreferencesService } from 'vs/workbench/services/preferences/common/preferences';
+import { withUndefinedAsNull } from 'vs/base/common/types';
 
 export const enum ConfigurationEditingErrorCode {
 
@@ -504,7 +505,7 @@ export class ConfigurationEditingService {
 
 			if (target === ConfigurationTarget.WORKSPACE) {
 				if (workbenchState === WorkbenchState.WORKSPACE) {
-					return workspace.configuration || null;
+					return withUndefinedAsNull(workspace.configuration);
 				}
 				if (workbenchState === WorkbenchState.FOLDER) {
 					return workspace.folders[0].toResource(relativePath);

src/vs/workbench/services/files/node/fileService.ts

@@ -42,6 +42,7 @@ import { onUnexpectedError } from 'vs/base/common/errors';
 import product from 'vs/platform/product/node/product';
 import { IEncodingOverride, ResourceEncodings } from 'vs/workbench/services/files/node/encoding';
 import { createReadableOfSnapshot } from 'vs/workbench/services/files/node/streams';
+import { withUndefinedAsNull } from 'vs/base/common/types';
 
 export interface IFileServiceTestOptions {
 	disableWatcher?: boolean;
@@ -464,7 +465,7 @@ export class FileService extends Disposable implements ILegacyFileService, IFile
 					}
 				};
 
-				let currentPosition: number | null = (options && options.position) || null;
+				let currentPosition: number | null = withUndefinedAsNull(options && options.position);
 
 				const readChunk = () => {
 					fs.read(fd, chunkBuffer, 0, chunkBuffer.length, currentPosition, (err, bytesRead) => {

src/vs/workbench/services/textfile/common/textFileEditorModel.ts

@@ -9,7 +9,7 @@ import { Event, Emitter } from 'vs/base/common/event';
 import { guessMimeTypes } from 'vs/base/common/mime';
 import { toErrorMessage } from 'vs/base/common/errorMessage';
 import { URI } from 'vs/base/common/uri';
-import { isUndefinedOrNull } from 'vs/base/common/types';
+import { isUndefinedOrNull, withUndefinedAsNull } from 'vs/base/common/types';
 import { IWorkspaceContextService } from 'vs/platform/workspace/common/workspace';
 import { IEnvironmentService } from 'vs/platform/environment/common/environment';
 import { ITextFileService, IAutoSaveConfiguration, ModelState, ITextFileEditorModel, ISaveOptions, ISaveErrorHandler, ISaveParticipant, StateChange, SaveReason, IRawTextContent, ILoadOptions, LoadReason, IResolvedTextFileEditorModel } from 'vs/workbench/services/textfile/common/textfiles';
@@ -492,7 +492,7 @@ export class TextFileEditorModel extends BaseTextEditorModel implements ITextFil
 			return Promise.resolve(null);
 		}
 
-		return this.backupFileService.resolveBackupContent(backup).then(backupContent => backupContent || null, error => null /* ignore errors */);
+		return this.backupFileService.resolveBackupContent(backup).then(withUndefinedAsNull, error => null /* ignore errors */);
 	}
 
 	protected getOrCreateMode(modeService: IModeService, preferredModeIds: string | undefined, firstLineText?: string): ILanguageSelection {