Start: middleware context property type gets merged instead of overridden

[acastroviejo]

Which project does this relate to?

Start

Describe the bug

If I try to override a context property on a second middleware the types get merged together instead of overridden.

Your Example Website or App

https://github.com/acastroviejo/start-merge-middleware-context

Steps to Reproduce the Bug or Issue

1. Open the ~/app/routes/index.tsx file and inspect the type of context.session (line 25)

Expected behavior

I expected the type of overridden context properties to be overridden and not merged together.

Screenshots or Videos

Platform

• OS: [e.g. macOS, Windows, Linux]
• Browser: [e.g. Chrome, Safari, Firefox]
• Version: [e.g. 91.1]

Additional context

A real world use case is a sessionMiddleware that uses a maybeSessionMiddleware internally updating the type of session from Session | undefined to Session, but now it stays as possibly undefined

[SeanCassiere]

cc @chorobin