When using the "errors" package, using `%+v` (extended format),
each Frame of the error's StackTrace will be printed in detail.
Let's only print `%v` to print the error.
If the error has a Cause it will be printed recursively.
Basically `%+v` has been replaced with `%v` for all `error` type
interfaces, whether the logger is Info, Warning or Error.
Signed-off-by: Sébastien Han <seb@redhat.com>