fix: non security related findings

[skosito]

https://github.com/zeta-chain/protocol-private/issues/189
https://github.com/zeta-chain/protocol-private/issues/183

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 7.69231% with 24 lines in your changes missing coverage. Please review.

Project coverage is 3.37%. Comparing base (2533cc1) to head (75c76c9).

Files with missing lines	Patch %	Lines
programs/gateway/src/lib.rs	7.69%	24 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##            main     #71      +/-   ##
========================================
- Coverage   5.85%   3.37%   -2.48%     
========================================
  Files          1       1              
  Lines        410     385      -25     
========================================
- Hits          24      13      -11     
+ Misses       386     372      -14     

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