Type Inference Issue in Svelte 5

[matheustavarestrindade]

Describe the bug

Description: In Svelte 5, I've encountered an issue with type inference when using the load function in +page.server.ts.

When I pass a direct object as an argument to the load function, the type inference fails on the corresponding +page.svelte file. However, if I encapsulate the object inside another object (e.g., { obj }), the type inference works correctly.

Steps to Reproduce:

Create a +page.server.ts file.
Implement a load function that returns a direct object with the type or null, e.g., return { key: value }.]

Attempt to use the returned data in the +page.svelte file and observe the lack of type inference.
Modify the load function to return an encapsulated object, e.g., return { obj: { key: value } }.
Observe that the type inference now works correctly.

Expected Behavior: The type inference should work correctly even when passing a direct object in the load function.

Actual Behavior: Type inference fails when passing a direct object, requiring encapsulation to work properly.

Reproduction

Direct object:

With encapsulation:

Logs

No response

System Info

System:
    OS: Windows 10 10.0.19045
    CPU: (24) x64 AMD Ryzen 9 5900X 12-Core Processor
    Memory: 21.66 GB / 63.91 GB
  Binaries:
    Node: 20.12.1 - C:\Program Files\nodejs\node.EXE
    npm: 10.8.2 - C:\Program Files\nodejs\npm.CMD
  Browsers:
    Edge: Chromium (127.0.2651.74)
    Internet Explorer: 11.0.19041.4355
  npmPackages:
    @sveltejs/adapter-auto: ^3.0.0 => 3.2.4
    @sveltejs/kit: ^2.0.0 => 2.5.24
    @sveltejs/vite-plugin-svelte: ^4.0.0-next.6 => 4.0.0-next.6
    svelte: ^5.0.0-next.238 => 5.0.0-next.238
    vite: ^5.0.3 => 5.4.2

Severity

annoyance

Additional Information

No response

[jasonlyu123]

This matches the actual runtime behavior. If you returned null or undefined the data props is an empty object.