Error in events/<id> page

Error occurs when you open the link in a new tab or when you go to the link directly. If you open it in the same tab by clicking "Read More", there is no error.

Here is the error:
<img width="1054" alt="54494345-1d399f80-4914-11e9-9264-cee568173041" src="https://user-images.githubusercontent.com/35568696/54585568-60e7f280-4a55-11e9-9ee8-c0e7e36bda03.png">
