Have you used AI?

No

Bug Description

tapable@2.3.1 throws uncaught HMR is disabled error in Webpack Dev Server unless devServer.hot is set to false in webpack.config.js.
This is new behaviour in v2.3.1 and not present in v2.3.0 or earlier, which does not require devServer.hot: false to be set (default is true).

Link to Minimal Reproduction and step to reproduce

Repo: https://github.com/mao-sz/tapable-hmr-bug

1. Clone repo and cd into it

2. Run npm i

3. Run npm run dev to start WDS and navigate to the localhost URL

4. Open browser console - observe uncaught error [HMR] Hot Module Replacement is disabled and no console log of foo

   

5. Checkout to the downgrade-2.3.0 branch

6. Delete node_modules/

7. Re-run npm i - this should install everything the same other than tapable@2.3.0

8. Re-run npm run dev to start WDS and navigate to the localhost URL

9. Open browser console - observe foo is logged and no HMR error is thrown

Expected Behavior

devServer.hot can be omitted i.e. left as default true, and no uncaught HMR error thrown when launching WDS.

Actual Behavior

Uncaught HMR error thrown in browser console when launching WDS and no bundled src JS executed.
Error only resolved if devServer.hot set to false in webpack.config.js which should not be required.

Environment

System:
    OS: Linux 6.19 Fedora Linux 43 (KDE Plasma Desktop Edition)
    CPU: (16) x64 AMD Ryzen 7 5700X 8-Core Processor
    Memory: 24.97 GB / 31.26 GB
  Binaries:
    Node: 24.12.0 - /home/maoshizhong/.nvm/versions/node/v24.12.0/bin/node
    Yarn: 1.22.22 - /usr/bin/yarn
    npm: 11.7.0 - /home/maoshizhong/.nvm/versions/node/v24.12.0/bin/npm
  Browsers:
    Chrome: 146.0.7680.153
    Firefox: 148.0.2
    Firefox Developer Edition: 148.0.2
  Packages:
    html-webpack-plugin: ^5.6.6 => 5.6.6 
    webpack: ^5.105.4 => 5.105.4 
    webpack-cli: ^7.0.2 => 7.0.2 
    webpack-dev-server: ^5.2.3 => 5.2.3

Is this a regression?

Yes (please specify version below)

Last Working Version

v2.3.0

Additional Context

No response