[Fix] Add null check for session_key in KvawareRouter

[keyuchen21]

Summary

Fixes #735

This PR adds a null check for the session_key argument in KvawareRouter.__init__().

Problem

When users run kvaware routing without specifying --session-key, the router fails with an unclear error because session_key is accessed without validation.

Solution

Added a null check that raises a clear ValueError if session_key is None, matching the existing behavior in SessionRouter:

if session_key is None:
    raise ValueError("KvawareRouter must be initialized with a session_key")

Testing

• Verified syntax is correct
• The fix follows the same pattern used in SessionRouter (line 191-192)

[gemini-code-assist]

Summary of Changes

Hello @keyuchen21, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request enhances the robustness and user experience of the KvawareRouter by addressing a potential runtime issue. Previously, the router would fail with an unclear error if the session_key was not provided during initialization. This change introduces explicit validation, ensuring that users receive an immediate and informative ValueError when session_key is missing, aligning its behavior with similar components like SessionRouter.

Highlights

• Null Check Implementation: Implemented a null check for the session_key argument within the KvawareRouter.__init__() method.
• Improved Error Handling: If session_key is None, a ValueError is now raised with a clear message, preventing obscure errors and aligning with SessionRouter's behavior.

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[gemini-code-assist]

Code Review

This pull request adds a necessary null check for the session_key in KvawareRouter.__init__, preventing potential runtime errors when it's not provided. The change is consistent with the validation already present in SessionRouter. I've suggested also adding a similar check for lmcache_controller_port to further improve the robustness of the initializer, as it seems to be susceptible to the same issue.

[zerofishnoodles]

Hi, Can you confirm this error still exists?

[keyuchen21]

@zerofishnoodles

• I tried to reproduce with bug: session_key args has no null check #735 here is the result, please see screenshot
• it looks good to me

[zerofishnoodles]

Thanks for the screenshot. I meant will there be an error without this PR. Because kvaware router doesn't have to have a session key.