This might seem a little strange, but I think cause as an argument name to Wrap and Wrapf is unnecessary. I wonder if err might be good enough?

Here are some reasons:

1. it's obvious that we're wrapping an error that caused the need to add context in the first place
2. there's only one argument of type error
3. it is possible the argument is not the 'root' cause, so in a sense, isn't the 'cause'
4. IDE plugins will autofil and most of the time, the variable name would be err so you could just tab past it

Very minor issue, and mainly I'm trying to save myself two key-presses each time I use this (which I will every day).