test(gno.land/sdk/vm): add unit tests for Msg*.ValidateBasic

[sunspirit99]

The vm Msg is not yet covered by unit tests

Contributors' checklist...

• Added new tests, or not needed, or not feasible
• Provided an example (e.g. screenshot) to aid review or the PR is self-explanatory
• Updated the official documentation or not needed
• No breaking changes were made, or a BREAKING CHANGE: xxx message was included in the description
• Added references to related issues and PRs
• Provided any useful hints for running manual tests
• Added new benchmarks to generated graphs, if any. More info here.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 60.95%. Comparing base (4f6ca96) to head (ef4e013).
Report is 5 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2855      +/-   ##
==========================================
+ Coverage   60.91%   60.95%   +0.04%     
==========================================
  Files         564      564              
  Lines       75273    75273              
==========================================
+ Hits        45851    45884      +33     
+ Misses      26053    26015      -38     
- Partials     3369     3374       +5     

Flag	Coverage Δ
contribs/gnodev	60.65% <ø> (-0.82%)	⬇️
contribs/gnofaucet	14.46% <ø> (-0.86%)	⬇️
gno.land	67.92% <ø> (+0.75%)	⬆️
gnovm	65.77% <ø> (ø)
misc/genstd	80.54% <ø> (ø)
misc/logos	20.23% <ø> (+0.35%)	⬆️
tm2	62.07% <ø> (+0.02%)	⬆️

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[ltzmaxwell]

LGTM, cross reference #2409 (review) for future improve, at least we can add PkgExistError for now.

[thehowl]

LGTM, cross reference #2409 (review) for future improve, at least we can add PkgExistError for now.

yes; though we already test it in keeper_test.go ;)