Error creating an assay stream

[kdp-cloud]

Error occurs when creating an assay stream.

A NoMethodError occurred in isa_assays#create:

  undefined method `policy=' for nil:NilClass

    @isa_assay.sample_type.policy = @isa_assay.assay.policy
                          ^^^^^^^^^
  app/controllers/isa_assays_controller.rb:48:in `create'

Does not occur when creating experimental ISA compliant assays.