Mix-in supporting registering deinit callbacks that delegate to a Closeable.
Used on Apps, which may throw exceptions during their initialization / constructor, resulting in the loss of a
reference to them with which to invoke any callbacks they'd registered.
Mix-in supporting registering deinit callbacks that delegate to a Closeable.
Used on Apps, which may throw exceptions during their initialization / constructor, resulting in the loss of a reference to them with which to invoke any callbacks they'd registered.