fix array.first

src/vs/base/common/arrays.ts

@@ -404,9 +404,8 @@ export function firstIndex<T>(array: ReadonlyArray<T>, fn: (item: T) => boolean)
 }
 
 export function first<T>(array: ReadonlyArray<T>, fn: (item: T) => boolean, notFoundValue: T): T;
-export function first<T>(array: ReadonlyArray<T>, fn: (item: T) => boolean): T | null;
-export function first<T>(array: ReadonlyArray<T>, fn: (item: T) => boolean, notFoundValue: T | null): T | null;
-export function first<T>(array: ReadonlyArray<T>, fn: (item: T) => boolean, notFoundValue: T | null = null): T | null {
+export function first<T>(array: ReadonlyArray<T>, fn: (item: T) => boolean): T | undefined;
+export function first<T>(array: ReadonlyArray<T>, fn: (item: T) => boolean, notFoundValue: T | undefined = undefined): T | undefined {
 	const index = firstIndex(array, fn);
 	return index < 0 ? notFoundValue : array[index];
 }

src/vs/workbench/browser/quickopen.ts

@@ -214,7 +214,7 @@ class QuickOpenRegistry implements IQuickOpenRegistry {
 	}
 
 	getQuickOpenHandler(text: string): QuickOpenHandlerDescriptor | null {
-		return text ? arrays.first<QuickOpenHandlerDescriptor>(this.handlers, h => strings.startsWith(text, h.prefix), null) : null;
+		return text ? (arrays.first<QuickOpenHandlerDescriptor>(this.handlers, h => strings.startsWith(text, h.prefix)) || null) : null;
 	}
 
 	getDefaultQuickOpenHandler(): QuickOpenHandlerDescriptor {