fix(koishi): fix session.channel overwritten

[Hieuzest]

No description provided.

[codecov]

Codecov Report

Attention: Patch coverage is 90.90909% with 2 lines in your changes missing coverage. Please review.

Project coverage is 87.10%. Comparing base (7f4d6f1) to head (dc1a0ce).

Files with missing lines	Patch %	Lines
packages/core/src/session.ts	90.90%	2 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1505   +/-   ##
=======================================
  Coverage   87.10%   87.10%           
=======================================
  Files          36       36           
  Lines        5552     5562   +10     
  Branches     1067     1072    +5     
=======================================
+ Hits         4836     4845    +9     
- Misses        716      717    +1     

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