Are types considered breaking changes?

[koterpillar]

#19711 changed the return type of webpack from Compiler to null | Compiler. This means any TypeScript user who updates will get a compilation failure over it.

Are types considered a part of the Webpack API that warrant breaking changes? Do you plan (or maybe already have) tests for types not breaking again without a major version update?

I haven't checked whether it was/is possible to get an actual null as a result of calling webpack. Could this happen before? Would you accept a type refinement PR (e.g. with overloads) that gives majority of users a Compiler without a null possibility?

[hai-x]

whether it was/is possible to get an actual null as a result of calling webpack. Could this happen before?

Yes, it's possible, for example, when encountering a schema validation error.

Would you accept a type refinement PR (e.g. with overloads) that gives majority of users a Compiler without a null possibility?

We can refine it using function overloading, but it only makes sense when callback isn't provided (i.e., webpack({ /* options */ })).