So a global error handler can be set up for vuejs like so.
Although the error handlers in vuejs will work okay with some errors that happen during rendering they will not work for errors in general within the vuejs instance or in the page in general. To handle all errors in the page you will want to attach an event to the window object.
When I start to work on a real vuejs example there are going to be times where I am going to want to work out some kind of error handling system. Things do not always work they way that they should, also often things do work they way that they should but a user may not know how to use what I have made. In any case there should be some kind of system in place to let a user know what went wrong if something did in fact go wrong.