* guix/packages.scm: Export `package-error?' and `package-input-error?'. * guix-build.in (guix-build): Catch `&package-input-error' conditions, print a human-readable message, and exit.
* guix/packages.scm: Export `package-error?' and `package-input-error?'. * guix-build.in (guix-build): Catch `&package-input-error' conditions, print a human-readable message, and exit.