fix: decode struct with pointer must be nil

[misyuari]

fix #472

[misyuari]

any comment? @goccy

[goccy]

Thank you for your contribution ! The changes are LGTM 👍
lint job is failing, please merge master once.

[misyuari]

Thank you for your contribution ! The changes are LGTM 👍 lint job is failing, please merge master once.

done 🚀

[codecov-commenter]

Codecov Report

Merging #473 (029656a) into master (3d5ab28) will increase coverage by 0.00%.
The diff coverage is 100.00%.

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Additional details and impacted files

@@           Coverage Diff           @@
##           master     #473   +/-   ##
=======================================
  Coverage   76.78%   76.78%           
=======================================
  Files          55       55           
  Lines       18921    18922    +1     
=======================================
+ Hits        14528    14529    +1     
  Misses       3759     3759           
  Partials      634      634           

[goccy]

Thank you !! Merged.