[Start] Server Fn Type instantiation is excessively deep and possibly infinite error

[alvarosevilla95]

Which project does this relate to?

Start

Describe the bug

createServerFn type inference breaks down on certain recursive types, that should otherwise be valid in terms of serialization as a valid response.

type JSONValue = null | string | number | boolean | { [value: string]: JSONValue } | JSONValue[]

export const test1 = createServerFn().handler(() => {
  return [] as JSONValue[]
})

export const test2 = createServerFn().handler(() => {
  const a: JSONValue = []
  // or const a: JSONValue = {}
  return a
})

export const test3 = createServerFn().handler<JSONValue>(() => {
  return []
})

all produce the following type error:

1. Type instantiation is excessively deep and possibly infinite. [2589]

Your Example Website or App

N/A

Steps to Reproduce the Bug or Issue

See above

Expected behavior

JSONValue would be a valid response type for a server function

Screenshots or Videos

No response

Platform

• Router / Start Version: 1.121.34

Additional context

No response

[smoothdvd]

similar type issue:

Argument of type '() => Promise<PaginatedDocs>' is not assignable to parameter of type 'ServerFn<"GET", "data", undefined, undefined, PaginatedDocs>'.
Type 'Promise<PaginatedDocs>' is not assignable to type 'Promise<{ docs: { id: number; title: string; description?: string | null | undefined; coverImage?: number | { id: number; uid?: string | null | undefined; originalFilename?: string | null | undefined; ... 12 more ...; focalY?: number | ... 1 more ... | undefined; } | null | undefined; ... 8 more ...; createdAt: stri...'.
Type 'Promise<PaginatedDocs>' is not assignable to type 'Promise<{ docs: { id: number; title: string; description?: string | null | undefined; coverImage?: number | { id: number; uid?: string | null | undefined; originalFilename?: string | null | undefined; ... 12 more ...; focalY?: number | ... 1 more ... | undefined; } | null | undefined; ... 8 more ...; createdAt: stri...'.
Type 'PaginatedDocs' is not assignable to type '{ docs: { id: number; title: string; description?: string | null | undefined; coverImage?: number | { id: number; uid?: string | null | undefined; originalFilename?: string | null | undefined; ... 12 more ...; focalY?: number | ... 1 more ... | undefined; } | null | undefined; ... 8 more ...; createdAt: string; }[];...'.
Types of property 'docs' are incompatible.
Type 'KnowledgeBase[]' is not assignable to type '{ id: number; title: string; description?: string | null | undefined; coverImage?: number | { id: number; uid?: string | null | undefined; originalFilename?: string | null | undefined; tenant: number | { ...; }; ... 11 more ...; focalY?: number | ... 1 more ... | undefined; } | null | undefined; ... 8 more ...; crea...'.
Type 'KnowledgeBase' is not assignable to type '{ id: number; title: string; description?: string | null | undefined; coverImage?: number | { id: number; uid?: string | null | undefined; originalFilename?: string | null | undefined; tenant: number | { ...; }; ... 11 more ...; focalY?: number | ... 1 more ... | undefined; } | null | undefined; ... 8 more ...; crea...'.
Types of property 'parent' are incompatible.
Type 'number | KnowledgeBase | null | undefined' is not assignable to type 'number | { id: number; title: string; description?: string | null | undefined; coverImage?: number | { id: number; uid?: string | null | undefined; originalFilename?: string | null | undefined; ... 12 more ...; focalY?: number | ... 1 more ... | undefined; } | null | undefined; ... 8 more ...; createdAt: string; } |...'.
Type 'KnowledgeBase' is not assignable to type 'number | { id: number; title: string; description?: string | null | undefined; coverImage?: number | { id: number; uid?: string | null | undefined; originalFilename?: string | null | undefined; ... 12 more ...; focalY?: number | ... 1 more ... | undefined; } | null | undefined; ... 8 more ...; createdAt: string; } |...'.ts(2345)

export type PaginatedDocs<T = any> = {
    docs: T[];
    hasNextPage: boolean;
    hasPrevPage: boolean;
    limit: number;
    nextPage?: null | number | undefined;
    page?: number;
    pagingCounter: number;
    prevPage?: null | number | undefined;
    totalDocs: number;
    totalPages: number;
};

export interface KnowledgeBase {
  id: number;
  title: string;
  description?: string | null;
  coverImage?: (number | null) | AgentAsset;
  knowledgeBaseId?: string | null;
  parent?: (number | null) | KnowledgeBase;
  documents?: {
    docs?: (number | DocumentsKnowledgeBase)[];
    hasNextPage?: boolean;
    totalDocs?: number;
  };
  videos?: {
    docs?: (number | VideosKnowledgeBase)[];
    hasNextPage?: boolean;
    totalDocs?: number;
  };
  members?: {
    docs?: (number | KnowledgeBasesMember)[];
    hasNextPage?: boolean;
    totalDocs?: number;
  };
  owner?: (number | null) | Member;
  tenant: number | Tenant;
  updatedAt: string;
  createdAt: string;
}

[nsb]

I'm facing the same issue. I ended up writing a mapper function that doesn't use the complex type (Kysely JSON value in my case). I don't understand how to overcome this issue. Would be amazing if this can be fixed or documented.