message: fix: No error is thrown when adding plug-ins repeatedly(#847)
  closes
diff: @@ -218,7 +218,10 @@ export abstract class ChildableComponent<O extends ComponentHost, C extends Comp
  }
  if (this._componentChildren[name]) {
  - throw new Error('The component `%s` has already been added.');
  + // Component already added so we will return the existing component
  + // TODO: add better logging around this because it could be unexpected but shouldn't be fatal
  + // See https://github.com/TypeStrong/typedoc/issues/846
  + return <T> this._componentChildren[name];
  } else {
  const component: T = typeof componentClass === 'function'
  ? new (<ComponentClass<T>> componentClass)(this)
  