- Avoid creating an NSDictionary with NULL context object (https://github.com/kode54/Cog/blob/master/Audio/Chain/InputNode.m#L81 passes NULL as context, so this must be handled in NSDictionary creation
- When calling addObserver, downgrade options from NSNumber * to NSKeyValueObservingOptions (aka NSUInteger)
Not sure why this would be specific to Apple Silicon...