Before Opening issues in the repository please check your exception here so you can solve your issue quickly.

Exception Message ‘Not Found’

{"message":"Not Found",
        "documentation_url":"https://developer.github.com/v3"}

This is due to invalid Token

Either dont have selected GIST option in scope while creating new token or not pasted the correct token.

Please reset the settings by sync reset settings command and then again try to download.

Check the Token exists in github with Gist Scope

Reference : GitHub

Goto Settings / Personal Access Tokens