createEventHook listener/trigger types aren't inferred properly

[romansp]

Describe the bug

There's a types inference regression introduced by #3507 for createEventHook listeners/triggers.

Previously arguments in on listeners would be correctly inferred from the type argument of createEventHook function. Today it will resolve to any when type argument is a union type. For projects with noImplicitAny enabled it now triggers an error.

It's also possible to omit arguments for trigger completely even though createEventHook was declared with a single type argument. See provided TS playground links.

Using typescript v5.2.2.

// 10.5.0
const numberOrStringHook = createEventHook<number | string>();
numberOrStringHook.on(value => {
  // value: number | string
});

// error: Expected 1 arguments, but got 0.
numberOrStringHook.trigger();

playground link

// 10.6.1
const numberOrStringHook = createEventHook<number | string>();
numberOrStringHook.on(value => {
  // value: any
});

// no errors
numberOrStringHook.trigger();

playground link

It also affected useFileDialog.onChange

import { useFileDialog } from "@vueuse/core";

const { onChange } = useFileDialog();
onChange(files => {
  // files is `any` but used to be `FileList | null`
});

playground link

Reproduction

https://www.typescriptlang.org/play?#code/JYWwDg9gTgLgBAbzgYygUwIYzQUQG5oB2MAEhBANZwC+cAZlBCHAEQACeArmpwM5oB6XgAsM6ACYsA3HAEC4MAJ5g0vAFxwAjAAYAdADZdmgLAAoM8giFe8QpxAAjNFDKU4AXhTosuAsVcUADx2js4AfAAUAJRSZiFOLuQUulYREXgYADbcUR5hiGZwRcUlpbICAHoA-GbUUWZx9gkBujBQwADmHc4RmjGNoYmUre1dPSw27YQdLP2m8c4tbZ3dUNGx802LSSMrPQh1GxZWNnALUADyUADKy9MBHl6Y2PhEpEnBW1BwAD5wk8BppE5ucrrcph0Wql0lkcnkCqYykjkeVqrV6uZNoMwXdITtlmM1n0NqCbrilqNVhEJrjZiSvjiIRS9msQQyyUz8ZT9ocGpjLNZ4HgIMBxA9PKhnr43gF1mZhaKoYQ0hlsmhcu58ghCiiinI0aY6nyFWKuSzenMTczCdSAdM6fKRabhgSqZandaqQc5kA

System Info

System:
    OS: macOS 14.1
    CPU: (10) arm64 Apple M1 Pro
    Memory: 215.66 MB / 32.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 18.18.2 - /usr/local/bin/node
    Yarn: 4.0.1 - /opt/homebrew/bin/yarn
    npm: 9.8.1 - /usr/local/bin/npm
    bun: 1.0.6 - ~/.bun/bin/bun
  Browsers:
    Chrome: 119.0.6045.159
    Safari: 17.1
  npmPackages:
    @vueuse/components: ^10.6.1 => 10.6.1 
    @vueuse/core: ^10.6.1 => 10.6.1 
    @vueuse/integrations: ^10.6.1 => 10.6.1 
    vue: ^3.3.8 => 3.3.8

Used Package Manager

yarn

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Make sure this is a VueUse issue and not a framework-specific issue. For example, if it's a Vue SFC related bug, it should likely be reported to https://github.com/vuejs/core instead.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion.
• The provided reproduction is a minimal reproducible example of the bug.

[kirk-loretz-fsn]

The type inference regression for useFileDialog.onChange is due to distributive conditional types.

vueuse/packages/core/useFileDialog/index.ts

Line 45 in 6040e1c

onChange: EventHookOn<FileList | null>

vueuse/packages/shared/createEventHook/index.ts

Lines 7 to 8 in 6040e1c

	type Callback<T> = T extends void ? () => void : (param: T) => void
	export type EventHookOn<T = any> = (fn: Callback<T>) => { off: () => void }

Changing the Callback type to this would help fix useFileDialog.onChange:

type Callback<T> = [T] extends [void] ? () => void : (param: T) => void

Typescript Playground