fix(go): bullet-proof against nil dereferences + more fuzzers

[odeke-em]

This change fixes a bunch of issues identified by Orijtech Inc's audit
of ics23 which is a critical cosmos-sdk dependency and as per reports
about the Dragonberry & Elderberry vulnerability reports, this package
was put back on our radar to further audit and voila that uncovered
some issues, some of which have beenfixed in this change. While here
also added more fuzzers. To ensure that the fuzzers can run alright,
added -short to any invocations of "go test".

Fixes #241
Fixes #242
Fixes #243

[codecov]

Codecov Report

Attention: 13 lines in your changes are missing coverage. Please review.

Comparison is base (c7c7288) 65.61% compared to head (1f01815) 38.66%.

❗ Current head 1f01815 differs from pull request most recent head ab5ea00. Consider uploading reports for the commit ab5ea00 to get more accurate results

Files	Patch %	Lines
go/proof.go	76.66%	6 Missing and 1 partial ⚠️
go/ops.go	66.66%	4 Missing and 2 partials ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           master     #244       +/-   ##
===========================================
- Coverage   65.61%   38.66%   -26.95%     
===========================================
  Files           7        5        -2     
  Lines        3621     4298      +677     
===========================================
- Hits         2376     1662      -714     
- Misses       1245     2314     +1069     
- Partials        0      322      +322     

Flag	Coverage Δ
go	38.66% <74.50%> (?)
rust	?

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[odeke-em]

Kindly cc-ing @crodriguezvega

[crodriguezvega]

Kindly cc-ing @crodriguezvega

Thank you for opening the issues and this PR, @odeke-em. I will review this week.

[crodriguezvega]

Thanks a lot for bulletproofing the code, @odeke-em! I have left a bunch of comments for now; let me know what you think about them.

[odeke-em]

/cc @elias-orijtech @julienrbrt

[crodriguezvega]

Thank you, @odeke-em. I still find weird that we need to explicitly check if the pointer receiver is nil. When I remove the check and run make test no tests fail... Maybe I am not running the tests correctly?

Besides, if that case was reachable, then why not add a similar check to all other functions with a pointer receiver?

[odeke-em]

Besides, if that case was reachable, then why not add a similar check to all other functions with a pointer receiver?

I mean the fuzzer flagged it but sure I did undo it. Kindly help me take another look @crodriguezvega and then merge if possible. Thank you!

[odeke-em]

Just cc-ing the cosmos-sdk team to remind us to pull in the updated release once this code is merged in /cc @tac0turtle @julienrbrt @elias-orijtech

[tac0turtle]

@odeke-em sdk team doesnt maintain this repo. Carlos and the ibc team are best to do merges and approvals here

[odeke-em]

Oh okay, gotcha and thank you @tac0turtle!

[AdityaSripal]

Thank you @odeke-em !