Fix some sneaky strict null issues for array/object access

TypeScript always assumes that array index access and object index type accesses return a non-null value. This was causing a few strict null issues to be masked where we were returning `array[i] || null` but the return type was not marked as nullable

The fix is to use `Map` types instead as these have the proper types

src/vs/editor/common/modes.ts

@@ -1565,9 +1565,9 @@ export interface ITokenizationRegistry {
 
 	/**
 	 * Get the tokenization support for a language.
-	 * Returns null if not found.
+	 * Returns `null` if not found.
 	 */
-	get(language: string): ITokenizationSupport;
+	get(language: string): ITokenizationSupport | null;
 
 	/**
 	 * Get the promise of a tokenization support for a language.

src/vs/editor/common/modes/languageConfigurationRegistry.ts

@@ -57,7 +57,7 @@ export class RichEditSupport {
 	public readonly indentationRules: IndentationRule | undefined;
 	public readonly foldingRules: FoldingRules;
 
-	constructor(languageIdentifier: LanguageIdentifier, previous: RichEditSupport, rawConf: LanguageConfiguration) {
+	constructor(languageIdentifier: LanguageIdentifier, previous: RichEditSupport | undefined, rawConf: LanguageConfiguration) {
 		this._languageIdentifier = languageIdentifier;
 
 		this._brackets = null;
@@ -175,34 +175,30 @@ export class LanguageConfigurationChangeEvent {
 
 export class LanguageConfigurationRegistryImpl {
 
-	private readonly _entries: RichEditSupport[];
+	private readonly _entries = new Map<LanguageId, RichEditSupport>();
 
 	private readonly _onDidChange = new Emitter<LanguageConfigurationChangeEvent>();
 	public readonly onDidChange: Event<LanguageConfigurationChangeEvent> = this._onDidChange.event;
 
-	constructor() {
-		this._entries = [];
-	}
-
 	public register(languageIdentifier: LanguageIdentifier, configuration: LanguageConfiguration): IDisposable {
 		let previous = this._getRichEditSupport(languageIdentifier.id);
 		let current = new RichEditSupport(languageIdentifier, previous, configuration);
-		this._entries[languageIdentifier.id] = current;
+		this._entries.set(languageIdentifier.id, current);
 		this._onDidChange.fire({ languageIdentifier });
 		return toDisposable(() => {
-			if (this._entries[languageIdentifier.id] === current) {
-				this._entries[languageIdentifier.id] = previous;
+			if (this._entries.get(languageIdentifier.id) === current) {
+				this._entries.set(languageIdentifier.id, previous);
 				this._onDidChange.fire({ languageIdentifier });
 			}
 		});
 	}
 
-	private _getRichEditSupport(languageId: LanguageId): RichEditSupport {
-		return this._entries[languageId] || null;
+	private _getRichEditSupport(languageId: LanguageId): RichEditSupport | undefined {
+		return this._entries.get(languageId);
 	}
 
 	public getIndentationRules(languageId: LanguageId) {
-		let value = this._entries[languageId];
+		const value = this._entries.get(languageId);
 
 		if (!value) {
 			return null;

src/vs/editor/common/modes/tokenizationRegistry.ts

@@ -7,11 +7,12 @@ import { Color } from 'vs/base/common/color';
 import { Emitter, Event } from 'vs/base/common/event';
 import { IDisposable, toDisposable } from 'vs/base/common/lifecycle';
 import { ColorId, ITokenizationRegistry, ITokenizationSupport, ITokenizationSupportChangedEvent } from 'vs/editor/common/modes';
+import { withUndefinedAsNull } from 'vs/base/common/types';
 
 export class TokenizationRegistryImpl implements ITokenizationRegistry {
 
-	private readonly _map: { [language: string]: ITokenizationSupport };
-	private readonly _promises: { [language: string]: Thenable<void> };
+	private readonly _map = new Map<string, ITokenizationSupport>();
+	private readonly _promises = new Map<string, Thenable<void>>();
 
 	private readonly _onDidChange = new Emitter<ITokenizationSupportChangedEvent>();
 	public readonly onDidChange: Event<ITokenizationSupportChangedEvent> = this._onDidChange.event;
@@ -19,8 +20,6 @@ export class TokenizationRegistryImpl implements ITokenizationRegistry {
 	private _colorMap: Color[] | null;
 
 	constructor() {
-		this._map = Object.create(null);
-		this._promises = Object.create(null);
 		this._colorMap = null;
 	}
 
@@ -32,13 +31,13 @@ export class TokenizationRegistryImpl implements ITokenizationRegistry {
 	}
 
 	public register(language: string, support: ITokenizationSupport) {
-		this._map[language] = support;
+		this._map.set(language, support);
 		this.fire([language]);
 		return toDisposable(() => {
-			if (this._map[language] !== support) {
+			if (this._map.get(language) !== support) {
 				return;
 			}
-			delete this._map[language];
+			this._map.delete(language);
 			this.fire([language]);
 		});
 	}
@@ -48,13 +47,13 @@ export class TokenizationRegistryImpl implements ITokenizationRegistry {
 		let registration: IDisposable | null = null;
 		let isDisposed: boolean = false;
 
-		this._promises[language] = supportPromise.then(support => {
-			delete this._promises[language];
+		this._promises.set(language, supportPromise.then(support => {
+			this._promises.delete(language);
 			if (isDisposed || !support) {
 				return;
 			}
 			registration = this.register(language, support);
-		});
+		}));
 
 		return toDisposable(() => {
 			isDisposed = true;
@@ -69,21 +68,21 @@ export class TokenizationRegistryImpl implements ITokenizationRegistry {
 		if (support) {
 			return Promise.resolve(support);
 		}
-		const promise = this._promises[language];
+		const promise = this._promises.get(language);
 		if (promise) {
-			return promise.then(_ => this.get(language));
+			return promise.then(_ => this.get(language)!);
 		}
 		return null;
 	}
 
-	public get(language: string): ITokenizationSupport {
-		return (this._map[language] || null);
+	public get(language: string): ITokenizationSupport | null {
+		return withUndefinedAsNull(this._map.get(language));
 	}
 
 	public setColorMap(colorMap: Color[]): void {
 		this._colorMap = colorMap;
 		this._onDidChange.fire({
-			changedLanguages: Object.keys(this._map),
+			changedLanguages: Array.from(this._map.keys()),
 			changedColorMap: true
 		});
 	}

src/vs/editor/test/common/modes/textToHtmlTokenizer.test.ts

@@ -18,7 +18,7 @@ suite('Editor Modes - textToHtmlTokenizer', () => {
 
 	test('TextToHtmlTokenizer 1', () => {
 		let mode = new Mode();
-		let support = TokenizationRegistry.get(mode.getId());
+		let support = TokenizationRegistry.get(mode.getId())!;
 
 		let actual = tokenizeToString('.abc..def...gh', support);
 		let expected = [
@@ -38,7 +38,7 @@ suite('Editor Modes - textToHtmlTokenizer', () => {
 
 	test('TextToHtmlTokenizer 2', () => {
 		let mode = new Mode();
-		let support = TokenizationRegistry.get(mode.getId());
+		let support = TokenizationRegistry.get(mode.getId())!;
 
 		let actual = tokenizeToString('.abc..def...gh\n.abc..def...gh', support);
 		let expected1 = [

src/vs/workbench/contrib/update/electron-browser/releaseNotesEditor.ts

@@ -209,7 +209,7 @@ export class ReleaseNotesManager {
 
 		renderer.code = (code, lang) => {
 			const modeId = this._modeService.getModeIdForLanguageName(lang);
-			return `<code>${tokenizeToString(code, modeId ? TokenizationRegistry.get(modeId) : undefined)}</code>`;
+			return `<code>${tokenizeToString(code, modeId ? TokenizationRegistry.get(modeId)! : undefined)}</code>`;
 		};
 		return renderer;
 	}