Test Suite: Snapshot Management
Test Case: Error Handling on Non-Existent Snapper Config

Description:
    This integration test verifies that the MCP server robustly handles errors
    when trying to interact with a non-existent snapper configuration. It sends
    a 'tools/call' request to the 'create_snapshot' tool with a non-existent config name
    ('non_existent_config_xyz') and verifies that the server correctly propagates
    a descriptive error response instead of generic messages.

Prerequisites:
    - None (the configuration should not exist).

Test Steps:
    1. Initialize the MCP server connection.
    2. Dispatch a 'create_snapshot' tool call with arguments containing:
       - config: 'non_existent_config_xyz'
       - type: 'single'
       - other standard parameters.
    3. Assert the server's response contains a valid JSON-RPC 'result'.
    4. Validate that 'isError' is present and evaluated to True in the result.
    5. Validate that 'content' includes a descriptive error message stating that the
       D-Bus call failed for the specific non-existent configuration.

Expected Result:
    The response succeeds at the RPC level but includes an 'isError' flag set to True and
    a descriptive text: `snapper create single snapshot "non_existent_config_xyz" D-Bus call failed...`.
