* fix: prevent panic on close of closed channel in worker client reconnection
- Use idiomatic Go pattern of setting channels to nil after closing instead of flags
- Extract repeated safe-close logic into safeCloseChannel() helper method
- Call safeCloseChannel() in attemptConnection(), reconnect(), and handleDisconnect()
- In safeCloseChannel(), check if channel is not nil, close it, and set to nil
- Also set streamExit to nil in attemptConnection() when registration fails
- This follows Go best practices for channel management and prevents double-close panics
- Improved code maintainability by eliminating duplication
* fix: prevent panic on close of closed channel in worker client reconnection
- Use idiomatic Go pattern of setting channels to nil after closing instead of flags
- Extract repeated safe-close logic into safeCloseChannel() helper method
- Call safeCloseChannel() in attemptConnection(), reconnect(), and handleDisconnect()
- In safeCloseChannel(), check if channel is not nil, close it, and set to nil
- Also set streamExit to nil in attemptConnection() when registration fails
- Document thread-safety assumptions: function is safe in current usage (serialized
in managerLoop) but would need synchronization if used in concurrent contexts
- This follows Go best practices for channel management and prevents double-close panics
- Improved code maintainability by eliminating duplication
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