1. Create h1 opened, save
2. Open, collapse h1, don't save
3. Refresh

In this case, h1 state will be read from localStorage, differ from JSON persisted state and onChange callback triggered. The problem is that view is not ready and getting value will result to Cannot read properties of undefined (reading 'state')

Solution add this.view check?

  handleChange = () => {
    if (!this.props.onChange || !this.view) return;

    this.props.onChange(() => {
      return this.value();
    });
  };