Set support_type to nil if it's not given

app/services/imports/scheme_location_import_service.rb

@@ -208,6 +208,8 @@ module Imports
 
     def support_type(xml_doc)
       type = safe_string_as_integer(xml_doc, "support-type")
+      return unless type
+
       Scheme::SUPPORT_TYPE.value?(type) ? type : 0
     end
   end

spec/services/imports/scheme_location_import_service_spec.rb

@@ -217,5 +217,14 @@ RSpec.describe Imports::SchemeLocationImportService do
         expect(location.scheme.support_type).to eq("Missing")
       end
     end
+
+    context "and support_type is not answered" do
+      before { location_xml.at_xpath("//scheme:support-type").content = "" }
+
+      it "sets the support type to nil" do
+        location = location_service.create_scheme_location(location_xml)
+        expect(location.scheme.support_type).to eq(nil)
+      end
+    end
   end
 end