Merge pull request #5580 from samvera/issue-5492

allow sub-collections to be created from collection page

app/services/hyrax/collections/nested_collection_query_service.rb

@@ -171,7 +171,7 @@ def self.valid_combined_nesting_depth?(parent:, child: nil, scope:)
       # @return [Fixnum] the largest number of collections in a path nested
       #   under this collection (including this collection)
       def self.child_nesting_depth(child:, scope:)
-        return 1 if child.nil?
+        return 1 unless child
         # The nesting depth of a child collection is found by finding the largest nesting depth
         # among all collections and works which have the child collection in the paths, and
         # subtracting the nesting depth of the child collection itself.