TypedResponse allows incompatible types

[haines]

What version of Remix are you using?

1.7.0

Steps to Reproduce

Use a TypedResponse<T> in place of a TypedResponse<U>, where T and U are incompatible.

const wat: TypedResponse<string> = json(42);

Expected Behavior

Compile errors due to the type mismatch.

Actual Behavior

No compile errors.

[suhasabhishek]

@machour Can I work on this?

[machour]

@suhasabhishek of course, help is always welcome!
Make sure to target the dev branch of this repo.

[dabdine]

Messing around with this, I found that the reason for this behavior is:

• Typescript's Body interface (which Response extends and TypedResponse intersects through Response) defines the json function as json(): Promise<any>.
• The override in TypedResponse does not properly handle Body.json()'s Promise<any> return type. I'm not an expert in Typescript generics, but I'm guessing it's because any is more weakly typed than anything else causing the stronger typed generic parameter T to be lost due to erasure.

The fix in my PR addresses this by Omitting the json function that is defined on Typescript's Body interface and redefining it with the more strongly typed version from TypedResponse.