fix: Fix NullPointerException(#830)

[gq-tang]

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[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Project coverage is 0.00%. Comparing base (8cdda4b) to head (d9c6bf0).

Files with missing lines	Patch %	Lines
internal/handler/registercenter.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@          Coverage Diff          @@
##            main    #832   +/-   ##
=====================================
  Coverage   0.00%   0.00%           
=====================================
  Files         15      15           
  Lines        497     497           
=====================================
  Misses       497     497           

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[cloudxxx8]

LGTM

[cloudxxx8]

@gq-tang please sign-off the commit, or DCO cannot be passed