adapter-cloudflare 4.2.0 broke waitUntil use inside hooks.server.ts (with prerendering)

Describe the bug

Using adapter-cloudflare 4.1.0, npm run build works fine. Upgrading to 4.2.0 causes npm run build to fail with:

✓ built in 3.21s
TypeError: Cannot read properties of undefined (reading 'waitUntil')

/Users/maemigh/arcana-website/node_modules/wrangler/wrangler-dist/cli.js:29573
            throw a;
            ^
Error: 500 /about
To suppress or handle this error, implement `handleHttpError` in https://kit.svelte.dev/docs/configuration#prerender
    at file:///Users/maemigh/arcana-website/node_modules/@sveltejs/kit/src/core/config/options.js:202:13
    at file:///Users/maemigh/arcana-website/node_modules/@sveltejs/kit/src/core/postbuild/prerender.js:65:25
    at save (file:///Users/maemigh/arcana-website/node_modules/@sveltejs/kit/src/core/postbuild/prerender.js:403:4)
    at visit (file:///Users/maemigh/arcana-website/node_modules/@sveltejs/kit/src/core/postbuild/prerender.js:236:3)
    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)

Node.js v21.5.0

Reproduction

use event.platform.context.waituntil inside hooks.server.ts and use prerendering

Logs

No response

System Info

System:
    OS: macOS 14.3.1
    CPU: (8) arm64 Apple M1
    Memory: 58.55 MB / 16.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 21.5.0 - /opt/homebrew/bin/node
    npm: 10.2.4 - /opt/homebrew/bin/npm
    pnpm: 8.7.0 - ~/Library/pnpm/pnpm
  Browsers:
    Brave Browser: 122.1.63.174
    Edge: 122.0.2365.92
    Firefox Nightly: 92.0a1
    Safari: 17.3.1
  npmPackages:
    @sveltejs/adapter-auto: ^3.0.0 => 3.1.1
    @sveltejs/adapter-cloudflare: ^4.2.0 => 4.2.0
    @sveltejs/kit: ^2.0.6 => 2.5.0
    @sveltejs/vite-plugin-svelte: ^3.0.0 => 3.0.2
    svelte: ^4.2.8 => 4.2.9
    vite: ^5.0.0 => 5.0.12

npx wrangler -v
 ⛅️ wrangler 3.34.2
-------------------

Severity

blocking an upgrade

Additional Information

No response

Start by reproducing the failure with adapter-cloudflare 4.2.0 using npm run build, prerendering, and waitUntil in hooks.server.ts; compare it with adapter-cloudflare 4.1.0. Trace the prerender failure around the undefined platform context. Done means the prerendered build completes without the waitUntil error.