[eslint-plugin-query] `no-void-query-fn` false positive on enum returns with TypeScript 6

[park-jemin]

Describe the bug

The no-void-query-fn rule incorrectly reports queryFn must return a non-undefined value when a queryFn returns a TypeScript enum member. This only occurs when using TypeScript 6.0.

On investigating, looks like we're implicitly relying on these values for TypeFlags which should be internal to TS.

const TypeFlags = {
  Void: 16384,
  Undefined: 32768,
} as const

function isIllegalReturn(checker: TypeChecker, type: Type): boolean {
  const awaited = checker.getAwaitedType(type)

  if (!awaited) return false

  if (awaited.isUnion()) {
    return awaited.types.some((t) => isIllegalReturn(checker, t))
  }

  return awaited.flags & (TypeFlags.Void | TypeFlags.Undefined) ? true : false
}

The underlying values for TypeFlags were reorderd in this change: microsoft/TypeScript#63084. This ends up actually testing for UniqueESSymbol | EnumLiteral instead of Void | Undefined as intended.

Steps to reproduce

On TypeScript 6, the below triggers the lint violation:

import { useQuery } from '@tanstack/react-query'

enum ExampleEnum {
  A,
}

export function useExampleEnum() {
  return useQuery({
    queryKey: ['exampleEnum'],
    queryFn: () => {
      return ExampleEnum.A
    },
  })
}

Expected behavior

Returning an enum value from queryFn should not trigger no-void-query-fn.

How often does this bug happen?

Every time

Screenshots or Videos

No response

Platform

all

Tanstack Query adapter

None

TanStack Query version

v5.99.0

TypeScript version

v6.0.2

Additional context

Quick fix addressing this: #10460