fix: replace panic with error handling in compatUnaryServerInterceptor

[zbchi]

Fix: Replace panic with a logged internal error in compatUnaryServerInterceptor, when a service returns (nil, nil)
or a non-*RPCResult type.

Why this is needed

Previously, such invalid responses caused the server goroutine to panic.
This change ensures the error is properly logged and returned to the client instead
Related to #3008

[Copilot]

Pull Request Overview

This PR improves error handling in the compatUnaryServerInterceptor by replacing panics with proper error logging and returning errors to clients when services return invalid responses ((nil, nil) or non-*RPCResult types).

Key changes:

• Added logger import for error logging
• Replaced panic with logged error and proper error response for nil response/nil error case
• Replaced panic with logged error and proper error response for non-RPCResult type case

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[codecov-commenter]

Codecov Report

❌ Patch coverage is 0% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 40.33%. Comparing base (60d1c2a) to head (2d87c85).
⚠️ Report is 646 commits behind head on develop.

Files with missing lines	Patch %	Lines
protocol/triple/triple_protocol/handler_compat.go	0.00%	4 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #3064      +/-   ##
===========================================
- Coverage    46.76%   40.33%   -6.44%     
===========================================
  Files          295      457     +162     
  Lines        17172    32425   +15253     
===========================================
+ Hits          8031    13078    +5047     
- Misses        8287    18085    +9798     
- Partials       854     1262     +408     

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[Alanxtl]

lgtm