guix command line behavior upon network failure or package build failure

[Andy Tai]

The user facing guix command has two modes of failure as I have seen,
when doing "guix upgrade" or "guix package -u":

1. if when downloading substitutes, if downloading fails due to
network conditions, the whole command errors out (exits)

2. if some software has to be built locally, and if the build fails,
the whole command errors out (exits)

is it possible to have the guix command keeps going and finishes other
works that may be unrelated to the failure, and finally prints out
messages about the packages that failed to update?    This would be
more user friendly and makes guix more usable for end users. Thanks