code: func (e *Error) GetData(key DataKey) interface{} {
  	if e.data != nil {
  		val, ok := e.data[key]
  		if ok {
  			return val
  		}
  		if boolWrapper(e.data[disableInheritance], false) {
  			return nil
  		}
  	}
  	return e.class.data[key]
  }
docs: // GetData returns the value associated with the given DataKey on this error
  // or any of its ancestors. Please see the example for SetData