fix(install): avoid local in top-level error handler

Capture the failing command status in a regular variable before printf so the script stays POSIX-safe.

Add an inline note that local is only valid inside functions.

Author: rdavid

app/install

@@ -7,9 +7,10 @@ set -- "$@" --quiet
 BSH="$(
 	CDPATH='' cd -- "$(dirname -- "$0" 2>&1)" 2>&1 && pwd -P 2>&1
 )"/../lib/base.sh || {
-	local err=$?
+	# Capture status before printf; local is invalid outside functions.
+	err=$?
 	printf >&2 %s\\n "$BSH"
-	exit $err
+	exit "$err"
 }
 
 # shellcheck disable=SC2034 # Variable appears unused.