Fixed ConditionalWeakTableUpgrader Handles the case where oldInstance == newInstance, or if the collection gets modified while being processed Simplify JsonSerializerOptionsUpgrader Directly process JsonConverters inside existing JsonSerializerOptions, without creating a new instance. Handles case where we can't create a new instance, and the options aren't mutable. Also make sure we process static fields in System.Text.Json assembly. Possible fix for #640 Add some more easy hotload skips to save a few milliseconds