refactor: remove err return and add unit tests for handle errors

[aramase]

• remove unused error in the function
• add unit tests for webhook handler errors

[codecov-commenter]

Codecov Report

Merging #1091 (c37b659) into main (4a889b7) will increase coverage by 1.59%.
Report is 1 commits behind head on main.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #1091      +/-   ##
==========================================
+ Coverage   53.89%   55.49%   +1.59%     
==========================================
  Files          36       36              
  Lines        2297     2294       -3     
==========================================
+ Hits         1238     1273      +35     
+ Misses       1014      980      -34     
+ Partials       45       41       -4     

Files Changed	Coverage Δ
pkg/webhook/webhook.go	86.26% <100.00%> (+6.19%)	⬆️

... and 1 file with indirect coverage changes