Remove the serial handler decorator

[trickeydan]

Fixes #448

[codeclimate]

Code Climate has analyzed commit 5f30758 and detected 0 issues on this pull request.

The test coverage on the diff in this pull request is 67.2% (95% is the threshold).

This pull request will bring the total coverage in the repository to 89.0% (-0.9% change).

View more on Code Climate.

[trickeydan]

Many of the type: ignore statements that are added in this PR are due to #489

[kierdavis]

I wonder if a context manager would do a better job of reducing the duplicated try..except blocks without breaking typing like decorators do...

For now, this is good (and has been needed for a long time). Thanks!

[trickeydan]

I wonder if a context manager would do a better job of reducing the duplicated try..except blocks without breaking typing like decorators do...

Context Managers would definitely circumvent the issues with typing that decorators suffer from. I think we should investigate this is the future.