Lazy Initialization does not work in middleware

Environment

  System:
    OS: macOS 15.4.1
    CPU: (8) arm64 Apple M1 Pro
    Memory: 81.23 MB / 16.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 22.15.0 - ~/.local/state/fnm_multishells/60896_1748120199386/bin/node
    Yarn: 1.22.22 - ~/.local/state/fnm_multishells/60896_1748120199386/bin/yarn
    npm: 10.9.2 - ~/.local/state/fnm_multishells/60896_1748120199386/bin/npm
    pnpm: 8.8.0 - ~/.local/state/fnm_multishells/60896_1748120199386/bin/pnpm
  Browsers:
    Chrome: 136.0.7103.114
    Edge: 136.0.3240.92
    Safari: 18.4
  npmPackages:
    @auth/unstorage-adapter: ^2.0.0 => 2.9.1 
    next: latest => 15.3.2 
    next-auth: beta => 5.0.0-beta.28 
    react: ^18.2.0 => 18.3.1 

Reproduction URL

https://github.com/paul-vd/reproduction-next-auth-lazy-initialization/commit/6b03b4e82dd3a5fb342e80efc8cbd14b0f657218

Describe the issue

When using next-auth in a middleware the request for the lazy initialization is undefined.

How to reproduce

1. pull the reproduction repository
2. run the dev server
3. navigate to http://localhost:3000/middleware-example

Expected behavior

The request should be defined

Start with the linked reproduction repository and run its development server. Navigate to http://localhost:3000/middleware-example, inspect how next-auth initializes in middleware, and verify that the request passed to lazy initialization is defined as expected.