This has come up before. If you want to read up on the details then please use the search button in the Forum and also search Hugo’s issue tracker on GitHub.
There was some discussion on GitHub aimed towards addressing this issue but in the end it was decided that when getJSON fails then a project’s build should also fail because this is -after all- an ERROR that needs to be fixed and not masked.
Also note that the above is a recap of the discussion (as I remember it). It is not my opinion.
My advice would be to stop fetching external assets this way.
For posterity it is always preferable to store a tweet’s JSON under /data/ and then simply call it via a shortcode as needed.