nixos/zsh: don’t be noisy when scripts are run with -u

When a script specifies the shell option “nounset” as part of the shebang (e.g.,
via “#!/usr/bin/env -S zsh -u”), our initialization scripts would produce error
messages of the form:

    __ETC_FOO_SOURCED: parameter not set

These messages could probably be confusing to users when running such scripts.
By providing a fall-back in the parameter expansion, we can avoid them.

This patch does not address interactive shell start-up, where such messages may
(or may not) be less problematic.

0 files changed, 0 insertions, 0 deletions