getComponent (componentName, maybe) {
    const componentRegistry = this.getComponentRegistry()
    if (!componentRegistry) throw new Error('Missing componentRegistry.')
    const ComponentClass = componentRegistry.get(componentName)
    if (!maybe && !ComponentClass) {
      throw new Error('No Component registered with name ' + componentName)
    }
    return ComponentClass
  }
Get a component class for the component name provided. Use this within the
    render method to render children nodes.

    @example

    ```
    render($$) {
      let el = $$('div').addClass('sc-my-component')
      let caption = this.props.node.getCaption() // some method that returns a node
      let CaptionClass = this.getComponent(caption.type)
      el.append($$(CaptionClass, {node: caption}))
      return el
    }
    ```

    @param  {String} componentName The component's registration name
    @param  {Boolean} maybe if `true` then does not throw when no Component is found
    TODO: this paramater should really be called 'strict' even if this
    is a breaking change

    @return {Class}                The ComponentClass