Check if GitHub CLI tool is installed

github/github-membership.sh

@@ -79,6 +79,13 @@ if [[ -z "${GH_TOKEN:-}" ]]; then
   export GH_TOKEN
 fi
 
+command -v gh >/dev/null 2>&1 || { 
+  echo >&2 "This script requires the GitHub CLI tool (gh), but it's not installed."
+  echo >&2 "Please download and install it from https://github.com/cli/cli."
+  echo >&2 "Aborting."
+  exit 1
+}
+
 case $ACTION in
   "list-active") list_active_membership ;;
   "list-pending") list_pending_membership ;;