Log invalid action called

Signed-off-by: Knut Ahlers <knut@ahlers.me>

bin/docker-credential-vault

@@ -59,12 +59,12 @@ function main() {
     check_command "${cmd}"
   done
 
-  case "${1:-help}" in
+  case "${1:-}" in
   get) get ;;
   erase) erase ;;
   store) store ;;
   *)
-    echo "Supported are only: get, erase, store'" >&2
+    echo "$(basename $0): Supported are only: get, erase, store (called '${1:-}')" >&2
     exit 1
     ;;
   esac