message: [Storage] arb_existent_kvs_and_nonexistent_keys should create at least one key
  The output of this function is given to `init_mock_db`, which asserts
  that there should be at least one key.
  Closes:
diff: @@ -58,7 +58,7 @@ prop_compose! {
  (existent_kvs, nonexistent_keys) in hash_map(
  any::<HashValue>(),
  any::<AccountStateBlob>(),
  - 0..num_kvs,
  + 1..num_kvs,
  )
  .prop_flat_map(move |kvs| {
  let kvs_clone = kvs.clone();
  