catch step panic in Guard

[zhiqiangxu]

It seems the error return value of vm.Step is always nil, the exceptional cases are handled by panic directly(e.g., HandleBranch/HandleJump/HandleRd).

So what actually needs to be guarded is the panic.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 74.97%. Comparing base (d340262) to head (c64d07c).
Report is 1043 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop   #12202      +/-   ##
===========================================
- Coverage    75.19%   74.97%   -0.22%     
===========================================
  Files           49       49              
  Lines         3656     3656              
===========================================
- Hits          2749     2741       -8     
- Misses         734      743       +9     
+ Partials       173      172       -1     

Flag	Coverage Δ
cannon-go-tests	74.97% <ø> (-0.22%)	⬇️

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see 1 file with indirect coverage changes

[Inphi]

@zhiqiangxu Please rebase this on develop so CI checks can pass.

[zhiqiangxu]

@zhiqiangxu Please rebase this on develop so CI checks can pass.

Done in 76bc53f.

[Inphi]

/ci authorize 76bc53f

[zhiqiangxu]

@Inphi , looks like there's a random CI failure irrelevant to this PR..

[Inphi]

@zhiqiangxu Could you please do another rebase on develop? The tests seem flaky and I've repeatedly re-ran the tests to no avail. Perhaps the flakes are fixed on develop.

[zhiqiangxu]

@zhiqiangxu Could you please do another rebase on develop? The tests seem flaky and I've repeatedly re-ran the tests to no avail. Perhaps the flakes are fixed on develop.

Done.

[Inphi]

/ci authorize 6458246