replace void 0 with undefined

extensions/html-language-features/server/src/modes/embeddedSupport.ts

@@ -59,7 +59,7 @@ export function getDocumentRegions(languageService: LanguageService, document: T
 					if (/["'](module|(text|application)\/(java|ecma)script)["']/.test(scanner.getTokenText())) {
 						languageIdFromType = 'javascript';
 					} else {
-						languageIdFromType = void 0;
+						languageIdFromType = undefined;
 					}
 				} else {
 					let attributeLanguageId = getAttributeLanguage(lastAttributeName!);

extensions/html-language-features/server/src/modes/htmlFolding.ts

@@ -54,7 +54,7 @@ function limitRanges(ranges: FoldingRange[], maxRanges: number) {
 
 	// compute each range's nesting level in 'nestingLevels'.
 	// count the number of ranges for each level in 'nestingLevelCounts'
-	let top: FoldingRange | undefined = void 0;
+	let top: FoldingRange | undefined = undefined;
 	let previous: FoldingRange[] = [];
 	let nestingLevels: number[] = [];
 	let nestingLevelCounts: number[] = [];

extensions/html-language-features/server/src/modes/javascriptMode.ts

@@ -58,7 +58,7 @@ export function getJavaScriptMode(documentRegions: LanguageModelCache<HTMLDocume
 			return {
 				getText: (start, end) => text.substring(start, end),
 				getLength: () => text.length,
-				getChangeRange: () => void 0
+				getChangeRange: () => undefined
 			};
 		},
 		getCurrentDirectory: () => '',

extensions/html-language-features/server/src/modes/languageModes.ts

@@ -91,7 +91,7 @@ export function getLanguageModes(supportedLanguages: { [languageId: string]: boo
 			if (languageId) {
 				return modes[languageId];
 			}
-			return void 0;
+			return undefined;
 		},
 		getModesInRange(document: TextDocument, range: Range): LanguageModeRange[] {
 			return documentRegions.get(document).getLanguageRanges(range).map(r => {