NCMP returns 500 error on searches endpoint when No DMi Handles registered

Summary

When you execute a query against the /ncmp/v1/ch/searches endpoint without any registered cmHandles, NCMP return a 500 error instead of empty response or not found code.

Sample request body against /ncmp/v1/ch/searches:

{
    "conditions": [
        {
            "name": "hasAllModules",
            "conditionParameters": [{
                "moduleName": "enm-GNBDU"
            }]
        }
    ]
}

Sample response:

{
"status": "500 INTERNAL_SERVER_ERROR",
"message": "Yang resource not found",
"details": "No yang resources found for [enm-GNBDU] in dataspace NFP-Operational."
} 

It could be any moduleName.

The expectation on the client side would be HTTP 404 Not found code, or 200 OK response code with empty body.