Bug: @shopify/app-bridge-react <Modal> throws "modal.hide is not a function" with mock-bridge

When using the official React <Modal> component from @shopify/app-bridge-react together with mock-bridge, the app crashes with:
```
TypeError: modal.hide is not a function
    at @shopify_app-bridge-react.js:52:13
    at commitHookEffectListMount
    ...```