tree shaking is enabled in development mode

[xiaoxiaojx]

Bug report

It is mentioned in the documentation that one of the conditions for tree shaking to be enabled is mode: production.

But I found that the development mode code disappeared. I never believed that it was caused by tree shaking, because the document was very sure that it would not be enabled, 😢 until I found this problem by debugging.

This is easy to reproduce, such as this warehouse xiaoxiaojx/webpack-issuer

What is the current behavior?
tree shaking is enabled in development mode

What is the expected behavior?
Modify the webpack documentation or fix the development mode bug

If it is confirmed to be a bug, I can contribute this pr

Other relevant information:
webpack version: 5.88.2

[webpack-bot]

This issue had no activity for at least three months.

It's subject to automatic issue closing if there is no activity in the next 15 days.

[webpack-bot]

Issue was closed because of inactivity.

If you think this is still a valid issue, please file a new issue with additional information.

[xiaoxiaojx]

This change caused webpack/webpack@e1b5a78

[xiaoxiaojx]

@alexander-akait @TheLarkInn

[alexander-akait]

@xiaoxiaojx Yeah, side effects optimizations are enabled in any mode to avoid big different between development and production, especial problems with side effects, because developers often make mistakes there, do you want to update our docs?

[xiaoxiaojx]

@alexander-akait Well, I'll update the documentation. #7096