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DefinePlugin: obj.MISSING?.method() compiles to undefined() instead of short-circuiting #21822
Description
Have you used AI?
Yes
Which part of webpack is affected?
optimization (tree-shaking, splitChunks, concatenation)
Bug Description
Starting in 5.108.0, this:
process.env.SOME_UNDEFINED_FLAG?.includes("foo");compiles to this, which crashes:
undefined("foo");Previously, it compiled correctly to:
({"NODE_ENV":"production"}).SOME_UNDEFINED_FLAG?.includes("foo");
Link to Minimal Reproduction and steps to reproduce
Steps:
- Run 'npm install'
- Run 'npm run build'
- Check the output in the dist folder, you get
undefined("foo")which crashes (can be tried in Chrome console).
Expected Behavior
Undefined env variables on process.env can be accessed without crashing.
Actual Behavior
All string method operations on undefined process.env variables crash
Environment
⬡ System:
────────────────────────────────────────────────────────────────────────
OS: macOS 26.6
CPU: (10) arm64 Apple M1 Pro
Memory: 461.42 MB / 32.00 GB
⬡ Binaries:
────────────────────────────────────────────────────────────────────────
Node: 24.19.0 - /Users/jacob/.local/state/fnm_multishells/12069_1787554964945/bin/node
Yarn: 1.22.22 - /opt/homebrew/bin/yarn
npm: 12.0.2 - /Users/jacob/.local/state/fnm_multishells/12069_1787554964945/bin/npm
⬡ Browsers:
────────────────────────────────────────────────────────────────────────
Brave Browser: 151.1.93.138
Chrome: 151.0.7922.174
Firefox: 145.0.2
Safari: 26.6
⬡ Packages:
────────────────────────────────────────────────────────────────────────
webpack: 5.109.2 → 5.109.2
webpack-cli: 7.2.2 → 7.2.2Is this a regression?
Yes (please specify version below)
Last Working Version
5.107.2
Additional Context
No response
Activity
fix: short-circuit a call reached through an undefined DefinePlugin m…
fix: throw on a non-optional read past an undefined DefinePlugin member
fix(define): throw on a non-optional read past an undefined member (#…