Double write when `writeToDisk` is `true`

[AdrianBannister]

Bug Description

When writeToDisk is set to true Webpack will emit to the default outputFileSystem (normally not memfs due to this logic), and then when the assetEmitted hook fires webpack-dev-middleware also writes the file to the same location (Compiler code, dev middlerware code).

I know there might be some case where someone provides a custom outputFileSystem, but for the common case this seems like a waste, no? I picked this up while debugging storybook.

Link to Minimal Reproduction and step to reproduce

https://github.com/AdrianBannister/webpack-dev-middleware-bug-report

Steps:

1. npm install
2. node test.js
3. See two console.log messages for the same file being written twice

Expected Behavior

Not to write twice when writeToDisk: true

Actual Behavior

Writing twice to disk for the same file and content.

Environment

System:
    OS: Linux 6.8 Ubuntu 22.04.5 LTS 22.04.5 LTS (Jammy Jellyfish)
    CPU: (8) x64 Intel(R) Xeon(R) Platinum 8375C CPU @ 2.90GHz
    Memory: 47.58 GB / 61.80 GB
  Binaries:
    Node: 24.12.0
    Yarn: 1.22.22
    npm: 11.6.2

Is this a regression?

No

Last Working Version

No response

Additional Context

I guess you could say this was "broken" in this PR #1537

[alexander-akait]

Yes, sounds like a bug, we should not hook when writeToDisk is true, feel free to send a PR