Fix panic threat when using type-cast for customClaims in validator

[osamingo]

Description

The threat of panicking should be curbed by receiving a second return value when executing the type-cast.

References

• CodeReviewComments: https://github.com/golang/go/wiki/CodeReviewComments#dont-panic
• Effective Go: https://go.dev/doc/effective_go#interface_conversions

Testing

• This change adds test coverage for new/changed/fixed functionality

Checklist

• I have read and agreed to the terms within the Auth0 Code of Conduct.
• I have read the Auth0 General Contribution Guidelines.
• I have reviewed my own code beforehand.
• I have added documentation for new/changed functionality in this PR.
• All active GitHub checks for tests, formatting, and security are passing.
• The correct base branch is being used, if not master.

[osamingo]

I would appreciate it if you would approve running GitHub Actions for this PR when you have time.

[osamingo]

@Widcket ping

[sergiught]

Thanks @osamingo for the contribution! I left a few comments.

[osamingo]

@sergiught I fixed it, PTAL.

[codecov-commenter]

Codecov Report

Base: 89.05% // Head: 89.09% // Increases project coverage by +0.03% 🎉

Coverage data is based on head (2bc0d47) compared to base (e9dbfc6).
Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #165      +/-   ##
==========================================
+ Coverage   89.05%   89.09%   +0.03%     
==========================================
  Files           7        7              
  Lines         274      275       +1     
==========================================
+ Hits          244      245       +1     
  Misses         23       23              
  Partials        7        7              

Impacted Files	Coverage Δ
validator/validator.go	88.75% <100.00%> (+0.14%)	⬆️

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[sergiught]

Hey @osamingo 👋🏻 thanks a lot for the changes and apologies it took so while to get back to you! Would you mind adding a test case for this as well in the validatior_test.go file? 🙏🏻

[sergiught]

Hey @osamingo 👋🏻 I had some time and went ahead and added the test cases missing. Thanks for the contribution again!