Make updateNode more robust

[JannikStreek]

Proposed feature
Currently, node updates for non existing nodes are dropped. In theory that sounds good, but in practice if the first request to add the node was dropped, every further request on that node will fail as well. We should think about creating the node instead if it does not exist during the update. Or even better: Check if an upsert logic would work: typeorm/typeorm#1090 (comment).