fix: getTokenById return token nil, make panic

[qinguoyi]

when id=0, getTokenById return token nil, make panic

[songquanpeng]

Thx~

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 6 lines in your changes missing coverage. Please review.

Project coverage is 1.29%. Comparing base (f977469) to head (a83fbe3).
Report is 9 commits behind head on main.

Files with missing lines	Patch %	Lines
controller/billing.go	0.00%	4 Missing ⚠️
model/token.go	0.00%	2 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##            main   #1728      +/-   ##
========================================
- Coverage   1.30%   1.29%   -0.01%     
========================================
  Files        144     144              
  Lines      10153   10159       +6     
========================================
  Hits         132     132              
- Misses     10007   10013       +6     
  Partials      14      14              

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