Add null annotations for `x: T[] = null`

This code pattern indicates that the type should be nullable

src/vs/base/browser/dom.ts

@@ -347,7 +347,7 @@ class AnimationFrameQueueItem implements IDisposable {
 	/**
 	 * The runners scheduled at the current animation frame
 	 */
-	let CURRENT_QUEUE: AnimationFrameQueueItem[] = null;
+	let CURRENT_QUEUE: AnimationFrameQueueItem[] | null = null;
 	/**
 	 * A flag to keep track if the native requestAnimationFrame was already called
 	 */

src/vs/base/parts/tree/browser/treeImpl.ts

@@ -179,7 +179,7 @@ export class Tree implements _.ITree {
 		return this.model.collapse(element, recursive);
 	}
 
-	public collapseAll(elements: any[] = null, recursive: boolean = false): WinJS.Promise {
+	public collapseAll(elements: any[] | null = null, recursive: boolean = false): WinJS.Promise {
 		return this.model.collapseAll(elements, recursive);
 	}
 

src/vs/base/parts/tree/browser/treeModel.ts

@@ -1030,7 +1030,7 @@ export class TreeModel {
 		return item.collapse(recursive);
 	}
 
-	public collapseAll(elements: any[] = null, recursive: boolean = false): WinJS.Promise {
+	public collapseAll(elements: any[] | null = null, recursive: boolean = false): WinJS.Promise {
 		if (!elements) {
 			elements = [this.input];
 			recursive = true;

src/vs/editor/browser/config/configuration.ts

@@ -62,7 +62,7 @@ export function restoreFontInfo(storageService: IStorageService): void {
 	if (typeof strStoredFontInfo !== 'string') {
 		return;
 	}
-	let storedFontInfo: ISerializedFontInfo[] = null;
+	let storedFontInfo: ISerializedFontInfo[] | null = null;
 	try {
 		storedFontInfo = JSON.parse(strStoredFontInfo);
 	} catch (err) {

src/vs/editor/browser/controller/textAreaHandler.ts

@@ -250,7 +250,7 @@ export class TextAreaHandler extends ViewPart {
 			const metadata = LocalClipboardMetadataManager.INSTANCE.get(e.text);
 
 			let pasteOnNewLine = false;
-			let multicursorText: string[] = null;
+			let multicursorText: string[] | null = null;
 			if (metadata) {
 				pasteOnNewLine = (this._emptySelectionClipboard && metadata.isFromEmptySelection);
 				multicursorText = metadata.multicursorText;

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

@@ -159,7 +159,7 @@ export class LanguagesRegistry {
 
 		resolvedLanguage.aliases.push(langId);
 
-		let langAliases: string[] = null;
+		let langAliases: string[] | null = null;
 		if (typeof lang.aliases !== 'undefined' && Array.isArray(lang.aliases)) {
 			if (lang.aliases.length === 0) {
 				// signal that this language should not get a name

src/vs/editor/contrib/dnd/dnd.ts

@@ -145,7 +145,7 @@ export class DragAndDropController implements editorCommon.IEditorContribution {
 			let newCursorPosition = new Position(mouseEvent.target.position.lineNumber, mouseEvent.target.position.column);
 
 			if (this._dragSelection === null) {
-				let newSelections: Selection[] = null;
+				let newSelections: Selection[] | null = null;
 				if (mouseEvent.event.shiftKey) {
 					let primarySelection = this._editor.getSelection();
 					let { selectionStartLineNumber, selectionStartColumn } = primarySelection;

src/vs/editor/contrib/folding/syntaxRangeProvider.ts

@@ -45,7 +45,7 @@ export class SyntaxRangeProvider implements RangeProvider {
 }
 
 function collectSyntaxRanges(providers: FoldingRangeProvider[], model: ITextModel, cancellationToken: CancellationToken): Thenable<IFoldingRangeData[] | null> {
-	let rangeData: IFoldingRangeData[] = null;
+	let rangeData: IFoldingRangeData[] | null = null;
 	let promises = providers.map((provider, i) => {
 		return Promise.resolve(provider.provideFoldingRanges(model, foldingContext, cancellationToken)).then(ranges => {
 			if (cancellationToken.isCancellationRequested) {

src/vs/editor/contrib/multicursor/multicursor.ts

@@ -476,7 +476,7 @@ export class MultiCursorSelectionController extends Disposable implements IEdito
 	}
 
 	public selectAll(findController: CommonFindController): void {
-		let matches: FindMatch[] = null;
+		let matches: FindMatch[] | null = null;
 
 		const findState = findController.getState();
 

src/vs/editor/standalone/common/monarch/monarchLexer.ts

@@ -518,8 +518,8 @@ class MonarchTokenizer implements modes.ITokenizationSupport {
 		// regular expression group matching
 		// these never need cloning or equality since they are only used within a line match
 		let groupActions: monarchCommon.FuzzyAction[] = null;
-		let groupMatches: string[] = null;
-		let groupMatched: string[] = null;
+		let groupMatches: string[] | null = null;
+		let groupMatched: string[] | null = null;
 		let groupRule: monarchCommon.IRule = null;
 
 		while (pos < lineLength) {
@@ -528,7 +528,7 @@ class MonarchTokenizer implements modes.ITokenizationSupport {
 			const groupLen0 = groupActions ? groupActions.length : 0;
 			const state = stack.state;
 
-			let matches: string[] = null;
+			let matches: string[] | null = null;
 			let matched: string | null = null;
 			let action: monarchCommon.FuzzyAction | monarchCommon.FuzzyAction[] = null;
 			let rule: monarchCommon.IRule = null;

src/vs/editor/test/common/model/textModelSearch.test.ts

@@ -16,7 +16,7 @@ suite('TextModelSearch', () => {
 
 	const usualWordSeparators = getMapForWordSeparators(USUAL_WORD_SEPARATORS);
 
-	function assertFindMatch(actual: FindMatch, expectedRange: Range, expectedMatches: string[] = null): void {
+	function assertFindMatch(actual: FindMatch, expectedRange: Range, expectedMatches: string[] | null = null): void {
 		assert.deepEqual(actual, new FindMatch(expectedRange, expectedMatches));
 	}
 

src/vs/platform/keybinding/common/keybindingResolver.ts

@@ -230,7 +230,7 @@ export class KeybindingResolver {
 	}
 
 	public resolve(context: IContext, currentChord: string, keypress: string): IResolveResult {
-		let lookupMap: ResolvedKeybindingItem[] = null;
+		let lookupMap: ResolvedKeybindingItem[] | null = null;
 
 		if (currentChord !== null) {
 			// Fetch all chord bindings for `currentChord`

src/vs/platform/keybinding/test/common/abstractKeybindingService.test.ts

@@ -86,8 +86,8 @@ suite('AbstractKeybindingService', () => {
 	let currentContextValue: IContext | null = null;
 	let executeCommandCalls: { commandId: string; args: any[]; }[] = null;
 	let showMessageCalls: { sev: Severity, message: any; }[] = null;
-	let statusMessageCalls: string[] = null;
-	let statusMessageCallsDisposed: string[] = null;
+	let statusMessageCalls: string[] | null = null;
+	let statusMessageCallsDisposed: string[] | null = null;
 
 	setup(() => {
 		executeCommandCalls = [];

src/vs/workbench/api/electron-browser/mainThreadEditor.ts

@@ -32,7 +32,7 @@ export class MainThreadTextEditorProperties {
 	}
 
 	private static _readSelectionsFromCodeEditor(previousProperties: MainThreadTextEditorProperties, codeEditor: ICodeEditor): Selection[] {
-		let result: Selection[] = null;
+		let result: Selection[] | null = null;
 		if (codeEditor) {
 			result = codeEditor.getSelections();
 		}

src/vs/workbench/api/node/extHostTreeViews.ts

@@ -122,7 +122,7 @@ class ExtHostTreeView<T> extends Disposable {
 	private static LABEL_HANDLE_PREFIX = '0';
 	private static ID_HANDLE_PREFIX = '1';
 
-	private roots: TreeNode[] = null;
+	private roots: TreeNode[] | null = null;
 	private elements: Map<TreeItemHandle, T> = new Map<TreeItemHandle, T>();
 	private nodes: Map<T, TreeNode> = new Map<T, TreeNode>();
 

src/vs/workbench/parts/codeEditor/electron-browser/languageConfiguration/languageConfigurationExtensionPoint.ts

@@ -141,7 +141,7 @@ export class LanguageConfigurationFileHandler {
 			return null;
 		}
 
-		let result: CharacterPair[] = null;
+		let result: CharacterPair[] | null = null;
 		for (let i = 0, len = source.length; i < len; i++) {
 			const pair = source[i];
 			if (!isCharacterPair(pair)) {
@@ -165,7 +165,7 @@ export class LanguageConfigurationFileHandler {
 			return null;
 		}
 
-		let result: IAutoClosingPairConditional[] = null;
+		let result: IAutoClosingPairConditional[] | null = null;
 		for (let i = 0, len = source.length; i < len; i++) {
 			const pair = source[i];
 			if (Array.isArray(pair)) {
@@ -211,7 +211,7 @@ export class LanguageConfigurationFileHandler {
 			return null;
 		}
 
-		let result: IAutoClosingPair[] = null;
+		let result: IAutoClosingPair[] | null = null;
 		for (let i = 0, len = source.length; i < len; i++) {
 			const pair = source[i];
 			if (Array.isArray(pair)) {

src/vs/workbench/parts/tasks/common/taskTemplates.ts

@@ -123,7 +123,7 @@ const maven: TaskEntry = {
 	].join('\n')
 };
 
-let _templates: TaskEntry[] = null;
+let _templates: TaskEntry[] | null = null;
 export function getTemplates(): TaskEntry[] {
 	if (!_templates) {
 		_templates = [dotnetBuild, msbuild, maven].sort((a, b) => {

src/vs/workbench/services/files/electron-browser/fileService.ts

@@ -1147,7 +1147,7 @@ export class StatResolver {
 		else {
 
 			// Convert the paths from options.resolveTo to absolute paths
-			let absoluteTargetPaths: string[] = null;
+			let absoluteTargetPaths: string[] | null = null;
 			if (options && options.resolveTo) {
 				absoluteTargetPaths = [];
 				options.resolveTo.forEach(resource => {

src/vs/workbench/services/preferences/common/keybindingsEditorModel.ts

@@ -254,11 +254,11 @@ export class KeybindingsEditorModel extends EditorModel {
 
 class KeybindingItemMatches {
 
-	public readonly commandIdMatches: IMatch[] = null;
-	public readonly commandLabelMatches: IMatch[] = null;
-	public readonly commandDefaultLabelMatches: IMatch[] = null;
-	public readonly sourceMatches: IMatch[] = null;
-	public readonly whenMatches: IMatch[] = null;
+	public readonly commandIdMatches: IMatch[] | null = null;
+	public readonly commandLabelMatches: IMatch[] | null = null;
+	public readonly commandDefaultLabelMatches: IMatch[] | null = null;
+	public readonly sourceMatches: IMatch[] | null = null;
+	public readonly whenMatches: IMatch[] | null = null;
 	public readonly keybindingMatches: KeybindingMatches | null = null;
 
 	constructor(private modifierLabels: ModifierLabels, keybindingItem: IKeybindingItem, searchValue: string, words: string[], keybindingWords: string[], completeMatch: boolean) {