Function prepareErrorPageParts

prepareErrorPageParts(
    event: ReactIncomingEvent,
    response: ReactOutgoingResponse,
    container: IContainer,
    snapshot: ResponseSnapshotType,
    fallback?: ElementType,
): Promise<PreparedPage>
Resolve a declared error page into the pieces a renderer displays.

Separate from preparePageParts for one reason: an error page's loader takes the error first and the event second, so it cannot share the call.
Parameters
- event: ReactIncomingEvent
  The incoming event.
- response: ReactOutgoingResponse
  The outgoing response.
- container: IContainer
  The service container.
- snapshot: ResponseSnapshotType
  The response snapshot.
- Optionalfallback: ElementType
  Rendered when the application declared no component for this error. A web renderer passes its HTML error page; a native one passes nothing, because a package that may be rendering native views cannot reach for HTML.
Returns Promise<PreparedPage>
The pieces to display.