Matrix issues when creating users from CLI

[minimalparts]

Something to investigate: when creating users from CLI, indexing works but search fails as soon as several themes are present in the index, because of an error when vstacking.

It is possible to fix the problem by changing this line:

PeARS-federated/app/search/score_pages.py

Line 78 in 8355afd

m = vstack((m, npz))

and wrapping the two numpy arrays into csr_matrix. So the question is what happens at matrix initialization stage that produces the issue.