[Bug]: docgen bug with export default function ...

[jdelStrother]

Describe the bug

Storybook 7 beta49 generates javascript containing things like:

try {
    // @ts-ignore
    DefaultButton.displayName = "DefaultButton";
    // @ts-ignore
    default.__docgenInfo = { "description": "", "displayName": "DefaultButton", "props": { "label": { "defaultValue": null, "description": "", "name": "label", "required": true, "type": { "name": "string" } } } };
    // @ts-ignore
    if (typeof STORYBOOK_REACT_CLASSES !== "undefined")
        // @ts-ignore
        STORYBOOK_REACT_CLASSES["src/stories/DefaultButton.tsx#DefaultButton"] = { docgenInfo: DefaultButton.__docgenInfo, name: "DefaultButton", path: "src/stories/DefaultButton.tsx#DefaultButton" };
}
catch (__react_docgen_typescript_loader_error) { }

which cause the browser to fail parsing with Unexpected keyword 'default'. Expected a closing '}' at the end of a block statement.

It occurs when writing default exports like this -

export default function DefaultButton(p: Props) {
    return <button>{p.label}</button>
}

but can be avoided by separating out the export:

function DefaultButton(p: Props) {
    return <button>{p.label}</button>
}
export default DefaultButton

To Reproduce

Checkout https://github.com/jdelStrother/storybook-snapshots, run yarn && yarn storybook, view in browser

System

Environment Info:

  System:
    OS: macOS 13.1
    CPU: (8) arm64 Apple M1 Pro
  Binaries:
    Node: 16.18.1 - /etc/profiles/per-user/jon/bin/node
    Yarn: 1.22.19 - /nix/store/imzxd8mj6airij3v9xh8yddvhzbvvv9n-yarn-1.22.19/bin/yarn
    npm: 8.19.2 - /etc/profiles/per-user/jon/bin/npm
  Browsers:
    Chrome: 109.0.5414.119
    Safari: 16.2
  npmPackages:
    @storybook/addon-essentials: ^7.0.0-beta.49 => 7.0.0-beta.49 
    @storybook/addon-interactions: ^7.0.0-beta.49 => 7.0.0-beta.49 
    @storybook/addon-links: ^7.0.0-beta.49 => 7.0.0-beta.49 
    @storybook/addon-storyshots: ^7.0.0-beta.49 => 7.0.0-beta.49 
    @storybook/blocks: ^7.0.0-beta.49 => 7.0.0-beta.49 
    @storybook/react: ^7.0.0-beta.49 => 7.0.0-beta.49 
    @storybook/react-webpack5: ^7.0.0-beta.49 => 7.0.0-beta.49 
    @storybook/testing-library: ^0.0.14-next.1 => 0.0.14-next.1

Additional context

This is presumably an issue with react-docgen-typescript/react-docgen-typescript-plugin, but thought it was worth highlighting here since the same code works fine in Storybook v6 and v7 beta 45. (I assume the issue is introduced here: #21095)

[shilman]

Shiver me timbers!! I just released https://github.com/storybookjs/storybook/releases/tag/v7.0.0-beta.50 containing PR #21147 that references this issue. Upgrade today to the @next NPM tag to try it out!

npx sb@next upgrade --prerelease

[shilman]

Will try to fix in the library and try again

[shilman]

Gadzooks!! I just released https://github.com/storybookjs/storybook/releases/tag/v7.0.0-beta.61 containing PR #21380 that references this issue. Upgrade today to the @next NPM tag to try it out!

npx sb@next upgrade --prerelease