feat: add Nullable type

packages/app-common/src/types/index.ts

@@ -1 +1,2 @@
 export * from './function';
+export * from './utils';

packages/app-common/src/types/utils.ts

@@ -0,0 +1 @@
+export type Nullable<T> = T | null;

packages/app-common/src/utils/asserts.ts

@@ -8,7 +8,7 @@ export function assert(value: unknown): asserts value {
 }
 
 /**
- * The function for asserting whether a value's type is `never` at compile time.
+ * The function for asserting whether a value's type is `never`.
  */
 export function assertIsNever(value: never): never {
     throw new Error(`Assertion Error: ${String(value)} should be "never" type.`);

packages/app-main/src/main/window/windowManager.ts

@@ -1,11 +1,12 @@
+import type { Nullable } from '@ter/app-common';
 import { WindowType, assertIsNever } from '@ter/app-common';
 
 import type { AbstractWindow } from './abstractWindow';
 import { MainWindow } from './mainWindow';
 import type { CloseWindowOption, CreateWindowOption } from './types';
 
 interface WindowStore {
-    [id: string]: AbstractWindow | null;
+    [id: string]: Nullable<AbstractWindow>;
 }
 
 export class WindowManager {

packages/app-renderer/src/MainWindow/pages/HomePage/components/Introduction/Introduction.tsx

@@ -1,11 +1,11 @@
-import type { AppDetails } from '@ter/app-common';
+import type { AppDetails, Nullable } from '@ter/app-common';
 
 import { Assets } from 'src/assets';
 
 import css from './Introduction.module.scss';
 
 interface IntroductionProps {
-    appDetails: AppDetails | null;
+    appDetails: Nullable<AppDetails>;
 }
 
 export function Introduction({ appDetails }: IntroductionProps): JSX.Element {

packages/app-renderer/src/MainWindow/redux/types.ts

@@ -1,9 +1,9 @@
-import type { AppDetails } from '@ter/app-common';
+import type { AppDetails, Nullable } from '@ter/app-common';
 
 import type { ReduxReducer } from 'src/utils/redux';
 
 export interface StoreState {
-    appDetails: AppDetails | null;
+    appDetails: Nullable<AppDetails>;
 }
 
 export type MainReducer<Payload = undefined> = ReduxReducer<StoreState, Payload>;

packages/app-renderer/src/hooks/__tests__/usePersistFn.test.tsx

@@ -1,3 +1,4 @@
+import type { Nullable } from '@ter/app-common';
 import { assert } from '@ter/app-common';
 import { act, render } from '@testing-library/react';
 import { noop } from 'lodash';
@@ -11,8 +12,8 @@ describe(`Test react hook \`${usePersistFn.name}\``, () => {
     validateHookValueNotChanged('should return the same callbacks', () => [usePersistFn(noop)]);
 
     it('should call the latest non-persist function', () => {
-        let count: number | null = null;
-        let increaseCount = null as (() => void) | null;
+        let count: Nullable<number> = null;
+        let increaseCount = null as Nullable<() => void>;
         expect(count).toBeNull();
         expect(increaseCount).toBeNull();