VectorStores list method errors out when no stores defined for a project

[vrurg]

When attempting to list vector stores of a project where no store created yet the method list results in:

Error: JSONDeserialize(Error("invalid type: null, expected a string", line: 4, column: 18))

Perhaps the problem is in field data of ListVectorStoresResponse is just a Vec whereas the API can return a JSON null for it.

The proper fix would be turning the Vec into Option<Vec>, but it's a breaking change.