Unity crashes when GetComponent()

Hi All! I have broken my brain to resolve the problem why "Unity Editor has stopped working". An exception appears while GetComponent<>() is called with the wrong type, for example via Expression Evaluating. I attached gif file with my actions to reproduce a problem. Could you help me, please? What's wrong with it.
Unity 2018.1.0f2
windows 10
visual studio 15.7.1
https://drive.google.com/open?id=1eoPSg2VYuaw6QRUx1n8_NVxekUW2rqxi
![alt text][1] [1]: /storage/temp/116764-111-198.png