Incompatability between plugin-webpack and NPM7

Preflight Checklist

• I have read the contribution documentation for this project.
• I agree to follow the code of conduct that this project follows, as appropriate.
• I have searched the issue tracker for a bug that matches the one I want to file, without success.

Issue Details

• Electron Forge Version:
  • 6.0.0-beta.53
• Electron Version:
  • 10.1.3
• Operating System:
  • Mac OS 10.15.7
• Last Known Working Electron Forge version::
  • n/a

Expected Behavior

The expected behavior is that electron-forge should work as-intended no matter the version of npm with which it is being executed.

Actual Behavior

Because of a change in how dependency resolution is processed as of npm@7 (recently released), electron-forge commands no longer run, at least for my project on my machine.

In these cases, the error reported here occurs - “TypeError: Cannot read property ‘createSnapshot’ of undefined”.

Digging into node_modules, I can confirm that there is a node_modules/webpack at version 5 and a /node_modules/@electron-forge/plugin-webpack/node_modules/webpack at version 4. This duplicate issue is almost surely what is causing the error.

Downgrading to npm@6 fixes the issue.

To Reproduce

1. NPM is on a version greater than 7.0.0. In my case, 7.0.2.
2. electron-forge is a local dev dependency to the project.
3. Some mysterious condition I haven’t yet cornered…

I’m posting this before I’ve found exactly what is causing this issue on this one project, but which fails to reproduce on npm@6 or on a plain npx create-electron-app my-new-app --template=webpack. My hope is that someone else is running into this and has some of the data I am missing.

[feljx]

Possibly related to this change in NPM?

Peer dependencies Automatically installing peer dependencies is an exciting new feature introduced in npm 7. In previous versions of npm (4-6), peer dependencies conflicts presented a warning that versions were not compatible, but would still install dependencies without an error. npm 7 will block installations if an upstream dependency conflict is present that cannot be automatically resolved.

As described, the issue is the webpack 4 dependency within the webpack plugin. Either upgrading to webpack 5 or declaring it as a peer dependency fixes the issue, not sure what the right course of action is since I don’t know my way around the codebase.

The bug occurs when using NPM 7 and generating a project with create-electron-app with the webpack (or typescript-webpack) template. To circumvent, switch to NPM 6 (latest node version would be 14.15.5) for generation, then switch back to NPM 7 and it’ll work fine (obviously you need a node version manager).

[malept]

The Webpack plugin uses Webpack 5 as of beta 56.