Missing network related papers for preprints

[jvwong]

Background: Related papers are attached to the (1) Document and (2) Entities. Issue: There are no related papers for preprints without a PMID

To reproduce

Create a new entry using eLife Reviewed Preprint as a paper ID: 10.7554/eLife.92411.2

Details

This bug stems from the indra.js module function semanticSearch({ query, documents }). In this case, the query is the article text associated with the parent Document:

"query": {
    "uid": null,
    "text": "Some text here."
  },

For a null uid, senantic search returns a HTTP status 422 silently and no related papers are attached to the element.