add warning logs for silent failures in RPC message handling

[anaslimem]

Summary

This PR adds warning logs for previously silent error cases in the RPC layer where message sending failures were being swallowed with .ok().

Changes

Added proper error logging in 4 locations:

1. TCP send failures - When sending messages to peer fails (e.g., peer disconnected)
2. Request channel full - When handler can't keep up with incoming requests
3. Error response send failures - When sending error responses back to peer fails
4. Notification channel full - When handler can't keep up with notifications

Why

Previously, when these operations failed (e.g., peer disconnected, channel buffer full), the errors were silently ignored with .ok().

Now, when these failures occur, you'll see warnings like:

• failed to send message to peer: Broken pipe
• failed to send request to handler, channel full
• failed to send notification to handler, channel full