Single fetch: returning submission.reply() with action results in type never.

[coji]

I have introduced single fetch and added the settings to tsconfig.json,
I added a setting to tsconfig.json, but when the return value of the conform submission.reply() used in the form validation was included
The type returned by useActionData is never.

tsconfig.json is as follows, with types added to the content created by create remix.

{
  "include": [
    "**/*.ts",
    "**/*.tsx",
    "**/.server/**/*.ts",
    "**/.server/**/*.tsx",
    "**/.client/**/*.ts",
    "**/.client/**/*.tsx"
  ],
  "compilerOptions": {
    "lib": ["DOM", "DOM.Iterable", "ES2022"],
    "types": [
      "@remix-run/node",
      "vite/client",
      "@remix-run/react/future/single-fetch.d.ts"
    ],
    "isolatedModules": true,
    "esModuleInterop": true,
    "jsx": "react-jsx",
    "module": "ESNext",
    "moduleResolution": "Bundler",
    "resolveJsonModule": true,
    "target": "ES2022",
    "strict": true,
    "allowJs": true,
    "skipLibCheck": true,
    "forceConsistentCasingInFileNames": true,
    "baseUrl": ".",
    "paths": {
      "~/*": ["./app/*"]
    },

    // Vite takes care of building everything, not tsc.
    "noEmit": true
  }
}

Reproduction

https://stackblitz.com/~/github.com/coji/conform-on-remix-single-fetch

System Info

System:
    OS: macOS 14.4.1
    CPU: (8) arm64 Apple M2
    Memory: 2.76 GB / 24.00 GB
    Shell: 5.9 - /bin/zsh
  npmPackages:
    @remix-run/dev: ^2.9.1 => 2.9.1 
    @remix-run/node: ^2.9.1 => 2.9.1 
    @remix-run/react: ^2.9.1 => 2.9.1 
    @remix-run/serve: ^2.9.1 => 2.9.1 
    vite: ^5.2.11 => 5.2.11

Used Package Manager

pnpm

Expected Behavior

The return type of useActionData is as follows.

{
    lastRusult: SubmissionResult<string[]>;
> | undefined
}

Actual Behavior

The type is never.

const actionData: never

Therefore, the following error is displayed in typecheck.

$ pnpm typecheck

> conform-on-remix-single-fetch@ typecheck /Users/coji/progs/spike/conform/conform-on-remix-single-fetch
> tsc

app/routes/_index.tsx:19:29 - error TS2339: Property 'lastResult' does not exist on type 'never'.

19     lastResult: actionData?.lastResult,
                               ~~~~~~~~~~


Found 1 error in app/routes/_index.tsx:19

[tobiasfoerg]

I ran into the same issue. This is because SubmissionResult has a prop with Result<string, unknown>.

[brophdawg11]

Yeah I agree. The types for single fetch are restricting loaders/actions to returning types we know can be serialized by turbo-stream and won't throw an error at runtime. The unknown is problematic since we can't know what it will be and can't be sure it's something turbo-stream knows how to serialize.

[coji]

@brophdawg11

Bumping to remix v2.9.2 eliminated the error.
Thank you very much!

https://stackblitz.com/~/github.com/coji/conform-on-remix-single-fetch/pull/2?file=app/routes/_index.tsx