Class components should not subscribe to state changes in the constructor. #103

If a component has be instantiated (constructor has executed) but not yet mounted, this.updater will be undefined. If the global state is accessed in the constructor, it will subscribe. If it changes before mount, it will attempt to update, throwing an error that this.updater does not exist.

Either check that this.updater exists or prevent subscribing in the constructor (if possible to differentiate).