Still raise if there's no #actual_namespace

However, we only need to raise for project_type clusters to maintain
previous behaviour.

In all probablity this requirement to have actual_namespace came from
KubernetesService and will no longer be required soon.

app/models/clusters/platforms/kubernetes.rb

@@ -156,6 +156,7 @@ module Clusters
 
       def build_kube_client!
         raise "Incomplete settings" unless api_url
+        raise "No namespace" if cluster.project_type? && actual_namespace.empty?  # can probably remove this line once we remove #actual_namespace
 
         unless (username && password) || token
           raise "Either username/password or token is required to access API"