Improve error handling

[jonathan-mayer]

Issue

Currently errors are handled by pre defined errors.New vars. This means that the value that caused the issue can't be shown to the user.

Problem to solve

There should be custom errors for those cases. They should also have custom values you can set to show the user the value / state that caused this issue.

Further details

Proposal

Implement some custom errors and replace the error vars with them.

Who can address the issue

Someone who has some experience in Go

Other links/references