Merge #4815

4815: Refactor code using onLeft and onNothing r=Jimbo4350 a=newhoggy

Using `onLeft` and `onNothing` gives more opportunities for straight line code.  Examples of this are marked.

Modifying the code elsewhere as well for general consistency.

This PR is divided into multiple commits to group related changes for easy review.

Note, `throwE` from `Control.Monad.Trans.Except` is the same as `left` from `Control.Monad.Trans.Except.Extra`.

Co-authored-by: John Ky <[email protected]>

Author: iohk-bors[bot]