在JavaScript中跟踪未定义的变量

Question

我收到以下错误：

libs.js:3392 TypeError: Cannot read property 'offsetHeight' of undefined
  at Object.b.updateAutoHeight (http://localhost:3000/.../scripts/libs.js:1529:12362)
  at Object.b.slideTo (http://localhost:3000/.../scripts/libs.js:1530:1740)
  at Object.b.init (http://localhost:3000/.../scripts/libs.js:1530:25098)
  at Object.t (http://localhost:3000/.../scripts/libs.js:1530:27249)
  at HTMLDivElement.<anonymous> (http://localhost:3000/.../scripts/libs.js:1529:107)
  at Function.each (http://localhost:3000/.../scripts/libs.js:1409:2882)
  at n.each (http://localhost:3000/.../scripts/libs.js:1409:847)
  at n.e.fn.swiper (http://localhost:3000/.../scripts/libs.js:1529:85)
  at Carousel.activate (http://localhost:3000/.../scripts/app.js:1802:34)
  at Carousel.toggleActivation (http://localhost:3000/.../scripts/app.js:1824:57)

现在我知道错误是某个变量被传递到库中，当它不应该是未定义的时候。如何回溯未定义的传递变量？