Fix that projects without content are at times served the wrong GraphQL content

[tanius]

output.txt
This issue happens only for projects that contain no content. Sometimes but not always, the request for the Graphql content ("POST http://graphryder.edgeryders.eu/graphql") will result in way too much content (57 MiB in my test, while expecting a few hundred bytes). In the browser, the symptom will that (1) it takes a very long time to load the dashboard and (2) eventually the dashboard will not appear but an error message like this:

Graph.addNode: the "user_8" node already exist in the graph.

Those 57 MiB of GraphQL content could possibly contain everything stored in the Graphryder Neo4J database. I have a local copy of such a 57 MiB reply and here are the first 60 kiB of that reply. In addition, this is the cUrl equivalent of the request that resulted in this 57 MiB reply:

curl 'http://graphryder.edgeryders.eu/graphql' \
  -X POST \
  -H 'content-type: application/json' \
  -H 'Origin: http://graphryder.edgeryders.eu' \
  -H 'Connection: keep-alive' \
  --data-raw '{"operationName":"getGraphByProject","variables":{"platform":"trustinplay","project":"A Town by the Sea (NOT IN USE)"},"query":"query getGraphByProject($platform: String!, $project: String!) {\n  graph: getGraphByProject(platform: $platform, project: $project) {\n    attributes\n    nodes {\n      key\n      attributes\n      __typename\n    }\n    edges {\n      key\n      source\n      target\n      attributes\n      __typename\n    }\n    __typename\n  }\n}\n"}' \
  > graphl.txt

This issue is connected with issue #25 in that both affect projects without content, but they are caused by different pieces of code.