Type checks doesn’t work when importing my types from a custom library

so basically, I’m working on a react-native library which exports some components and utilities to improve overall development.

In this library, I have a light and dark Theme, which I want to be able to override in my app code. To make this easier and intuitive, I want to import the type definition of a Theme from my library.

These 2 files comes from my library :

**src/types/CustomTheme.ts
declare type CustomTheme = {
  dark: boolean;
  colors: {
    primary: string;
    background: string;
    card: string;
    text: string;
    textOnPrimary: string;
    border: string;
    variant: string;
    notification: string;
    inversed: string;
  };
  text: {
    lg: number;
    med: number;
    sm: number;
  };
};
export default CustomTheme;

**src/index.tsx
// Types for theme
import type CustomTheme from './types/CustomTheme';
export type { CustomTheme };

Then in my react-native app i’m doing :

import { type CustomTheme } from 'my-library';

let CustomLightTheme: CustomTheme = {
  // Here VScode doesn't tells me that 'CustomLightTheme' is missing a lot of properties
};

Even if there is no errors, type checking is not really done here. For example, VSCode is not telling that my object miss some properties.

How can i have these kind of type checks when importing a type from my library ?