`build.rollupOptions.dir` and `build.rollupOptions.file` no longer work as expected

Describe the bug

I have been using vite 2.9 before updating to 3.2.4 and building a single bundle.js file with npm run build. After updating – it has become no longer possible to build the app to a single file due to one of the following errors:

Error no. 1:

TypeError [ERR_INVALID_ARG_TYPE]: The "path" argument must be of type string. Received null

or Error no.2:

Error: Invalid value for option "output.dir" - you must set either "output.file" for a single-file build or "output.dir" when generating multiple chunks

Essentially, specifying dir: null which has worked previously now gives the “Error no. 1” output Meanwhile, specifying ONLY file: ... now gives “Error no. 2” output.

Both errors seem to conflict with one another leading to an endless cycle of resolving one - points to another and vice versa.

Reproduction

https://github.com/kgataveckastg/vite-dir-file-bug

Steps to reproduce

yarn create vite --template=react-ts

vite.config.ts:

import { defineConfig } from 'vite'
import react from '@vitejs/plugin-react'
import path from 'path';

// https://vitejs.dev/config/
export default defineConfig({
  plugins: [react()],
  build: {
    rollupOptions: {
      output: {
        file: path.resolve('./dist', 'bundle.js'),
        format: 'iife',
      }
    }
  }
})

Run npm run build

System Info

System:
    OS: macOS 13.0.1
    CPU: (12) x64 Intel(R) Core(TM) i7-9750H CPU @ 2.60GHz
    Memory: 818.66 MB / 16.00 GB
    Shell: 5.8.1 - /bin/zsh
  Binaries:
    Node: 16.17.1 - /usr/local/bin/node
    Yarn: 1.22.4 - /usr/local/bin/yarn
    npm: 8.15.0 - /usr/local/bin/npm
  Browsers:
    Brave Browser: 105.1.43.93
    Chrome: 103.0.5060.114
    Safari: 16.1
  npmPackages:
    @vitejs/plugin-react: ^2.2.0 => 2.2.0 
    vite: ^3.2.4 => 3.2.4 

### Used Package Manager

npm

### Logs

_No response_

### Validations

- [X] Follow our [Code of Conduct](https://github.com/vitejs/vite/blob/main/CODE_OF_CONDUCT.md)
- [X] Read the [Contributing Guidelines](https://github.com/vitejs/vite/blob/main/CONTRIBUTING.md).
- [X] Read the [docs](https://vitejs.dev/guide).
- [X] Check that there isn't [already an issue](https://github.com/vitejs/vite/issues) that reports the same bug to avoid creating a duplicate.
- [X] Make sure this is a Vite issue and not a framework-specific issue. For example, if it's a Vue SFC related bug, it should likely be reported to [vuejs/core](https://github.com/vuejs/core) instead.
- [X] Check that this is a concrete bug. For Q&A open a [GitHub Discussion](https://github.com/vitejs/vite/discussions) or join our [Discord Chat Server](https://chat.vitejs.dev/).
- [X] The provided reproduction is a [minimal reproducible example](https://stackoverflow.com/help/minimal-reproducible-example) of the bug.

[sapphi-red]

An example is:

export default defineConfig({
  plugins: [react()],
  build: {
    rollupOptions: {
      output: {
        dir: path.resolve('./dist'),
        entryFileNames: 'bundle.js',
        format: 'iife',
      }
    }
  }
})

[kgataveckastg]

Thank you, it looks to be working fine now.