[Web] Handle LocalSession init in WASM RPC server

[guan404ming]

Why

When a client connects without session_constructor_args, the RPC protocol sends nargs=0 (LocalSession request). The WASM RPC server requires ["rpc.WasmSession", wasm_binary] instead.

How

Adds handling to skip LocalSession init packets and wait for the proper WasmSession init, with a log message for debugging.

[gemini-code-assist]

Summary of Changes

Hello @guan404ming, 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 of the WebAssembly (WASM) RPC server by refining its session initialization process. It specifically ensures that the server can gracefully handle initial connection attempts that do not conform to the expected WASM session format, preventing premature or incorrect session establishment and improving overall client compatibility.

Highlights

• WASM RPC Server Initialization: The pull request addresses an issue where the WASM RPC server incorrectly handles LocalSession initialization requests (identified by nargs=0) when it expects a WasmSession initialization with specific arguments.
• Skipping LocalSession Init: New logic has been added to web/src/rpc_server.ts to detect LocalSession init requests. Upon detection, the server now skips this initialization and transitions its state to await the correct WasmSession init.
• Debugging and State Management: A log message is introduced to indicate when a LocalSession init is received and the server is waiting for WasmSession init, aiding in debugging. The server's state is also correctly updated to ReceivePacketHeader to continue processing.

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[gemini-code-assist]

Code Review

This pull request provides a fix for the WASM RPC server, which previously crashed when receiving a LocalSession initialization request. The change correctly identifies these requests (where nargs=0) and skips them, waiting for the proper WasmSession initialization packet. The implementation is straightforward and effective, improving the server's robustness by gracefully handling this specific client behavior. The added log message is also useful for debugging.