fix: donwgrade webpack version and adapt ts types

[grubyak]

• downgrade webpack
• adjust the config
• fix some ts lint errors

[ChazUK]

Out of interest why are you down grading the Webpack version?

[grubyak]

Out of interest why are you down grading the Webpack version?

that's due to some breaking changes that are affecting our local development, but we will upgrade again soon after solving the problem