Refactor errors

[liamsi]

Consistent error handling across the repo.
I have written up some notes briefly explaining what "consistent" means here. Will post them Posted in #150 (comment). They can be used for an ADR if that's desired.

closes #150

• Referenced an issue explaining the need for the change
• Updated all relevant documentation in docs
• Updated all code comments where relevant
• Wrote tests
• Updated CHANGES.md

[liamsi]

codecov wasn't reporting because of a missing report for the base commit. Deleted its comment.

[xla]

Tis extra dope!

Generally I'd err on the side of more qualification so use crate::error and then error::Error and error::Kind. Also left some remarks inline. ✌️

[codecov-io]

Codecov Report

Merging #158 into master will increase coverage by 0.07%.
The diff coverage is 45.45%.

@@            Coverage Diff            @@
##           master    #158      +/-   ##
=========================================
+ Coverage   37.42%   37.5%   +0.07%     
=========================================
  Files          91      91              
  Lines        3140    3144       +4     
  Branches      484     485       +1     
=========================================
+ Hits         1175    1179       +4     
- Misses       1690    1691       +1     
+ Partials      275     274       -1

Impacted Files	Coverage Δ
tendermint/src/lite/error.rs	47.05% <0%> (+0.9%)	⬆️
tendermint/src/lite/types.rs	49.13% <0%> (+0.56%)	⬆️
tendermint-lite/src/main.rs	0% <0%> (ø)	⬆️
tendermint/src/lite_impl/signed_header.rs	78.84% <44.44%> (ø)	⬆️
tendermint/src/lite/verifier.rs	74.7% <61.11%> (-0.5%)	⬇️

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[xla]

Generally I'd err on the side of more qualification so use crate::error and then error::Error and error::Kind.

@liamsi Think this could be addressed in this PR.

Otherwise: 🤘 🎥 🎊 🗞

[liamsi]

Merging as is now. Will address below in a separate PR which will add an ADR, too.

Generally I'd err on the side of more qualification so use crate::error and then error::Error and error::Kind.