ReactCSSTransitionGroup位置未定义

Question

我正在尝试使用ReactCSSTransitionGroup进行React路由器转换，并遵循了文档中的示例，但是得到了以下Uncaught TypeError: Cannot read property 'key' of undefined

我在做什么错？为什么未定义位置？

   render() {
        const {categories, language, location, reviews, subCategories} = this.props

        return(
          <Wrap>
            <Router>
              <ScrollToTop>
              <Header categories={categories} language={language} />
                <Wrap>
                  <TransitionGroup>
                  <CSSTransition
                    key={location.key}
                    timeout={{ enter: 300, exit: 300 }}
                    classNames={'fade'}
                  >
                      <Switch location={location}>
                        <Route exact path="/" render={props => <Home categories={categories} subCategories={subCategories} reviews={reviews} language={language} {...props} />} />
                        <Route exact path="/:catId" render={props => <ReviewsFilteredByCategory categories={categories} subCategories={subCategories} language={language} {...props} />} />
                        <Route exact path="/:catId/:slug" render={props => <ReviewsTop10 categories={categories} subCategories={subCategories} reviews={reviews} language={language} {...props} />} />
                      </Switch>
                    </CSSTransition>
                  </TransitionGroup>
                </Wrap>
                <Footer />
              </ScrollToTop>
            </Router>
          </Wrap>
        )
      }
    }