Description:

When running C++ KVS tests, if a defaults file (like kvs_1_default.json) is present but the hash file is missing, the test fails. The Rust version works fine without the hash file.

Steps to reproduce:

• Create a valid defaults file (e.g., kvs_1_default.json).
• Do not create a hash file for it.
• Run the C++ scenario.
• It fails with an error about the missing hash file.

Expected:

C++ KVS should load the defaults file even if the hash file is missing, just like Rust.

Actual:

C++ KVS fails if the hash file is missing.