Root cause: Lines 1414-1415 were trying to access non-existent fields
'stream_count' and 'attached' directly from channel objects. These values
are actually stored in the channel_stream_counts dictionary and
channels_attached_to_others set respectively.
Changes:
- Fixed field access to use correct data structures
- Added error handling to check if channel exists in stream_counts
- Added debug logging to show evaluation details for each channel
- Added full traceback logging in exception handler for better debugging
This fixes the error: "Error managing channel visibility: 'stream_count'"
