Dria HNSW crashes on newly uploaded knowledge

[erhant]

Since indexing takes some time on our servers, there is a moment where the contract is deployed but indexing transactions are still being processed.

If during that time, we connect to the contract with docker compose, we may crash the server. In particular we can call dria/fetch and it returns code 500, but another fetch after that crashes the server.

@andthattoo Actix may need a particular error-handling, or suggest the user to wait a bit. Also, the errors are printed to be Redis connection error, hiding the actual error below.