Vault returns 404 when Keys are not present

The vault returns during the key listing (https://gitlab.com/gaia-x/data-infrastructure-federation-services/tsa/signer/-/blob/main/internal/clients/vault/client.go#L91) a 404 response, when the engine is present, but no keys are in it:

This results then in a exception from signer service like this:

{"level":"error","ts":"2023-01-05T15:00:15Z","caller":"signer/service.go:164","msg":"error getting all verification methods","operation":"getKeys","namespace":"did-management.did-web-integration.gxfs.dev-api-dynamic-did-d","did":"did:web:integration.gxfs.dev:api:dynamic:did:d","error":"not found: Error making API request.\n\nURL: LIST http://vault:8200/v1/did-management.did-web-integration.gxfs.dev-api-dynamic-did-d/keys\nCode: 404. Errors:\n\n (518srJ3kyRXbLXaf)"}

The error is catched and returned, but actually this error is meaningless. In the best case we will have an pre check for key existence. Plan B could be to exclude the error handling when this particular error is popping up.

Seems like an vault misbehavior, when no keys are present in the engine.