Type information missing for "loaders"

Describe the bug There is no TypeScript type information for any of the loaders feature.

In particular, there is no loaders property on Story/BaseStory.

To Reproduce

export const Default = Template.bind({});
Default.loaders = createLoaders();

TS2339: Property ‘loaders’ does not exist on type 'Story '.

System

  System:
    OS: Windows 10 10.0.18363
    CPU: (8) x64 Intel(R) Core(TM) i7-9700K CPU @ 3.60GHz
  Binaries:
    Node: 14.15.3 - C:\Program Files\nodejs\node.EXE
    Yarn: 1.22.10 - ~\AppData\Roaming\npm\yarn.CMD
    npm: 6.14.9 - C:\Program Files\nodejs\npm.CMD
  Browsers:
    Chrome: 91.0.4472.106
    Edge: Spartan (44.18362.1593.0)
  npmPackages:
    @storybook/addon-actions: ^6.3.0 => 6.3.0
    @storybook/addon-essentials: ^6.3.0 => 6.3.0
    @storybook/addon-links: ^6.3.0 => 6.3.0
    @storybook/html: ^6.3.0 => 6.3.0

[phbernard]

A workaround, based on Storybook example:

type TodoItemStory = {
  loaders?: (() => Promise<any>)[];
} & Story<TodoItemProps>;

export const Primary: TodoItemStory = (args: TodoItemProps, { loaded: { todo } }) => <TodoItem {...args} todo={todo} />;

Primary.loaders = [
  async () => ({
    todo: (await fetch('https://jsonplaceholder.typicode.com/todos/1')).json(),
  }),
];

[unional]

Type assertion (as) is fine in this case.

What you can do further is to create a type alias, so it will save you some typing:

type Story = ComponentStory<typeof MyComponent> & { loaders: ... }

so you can use the same Story type in each of your story in the file.