Fix issues importing services via Import/Export

CHANGELOG

@@ -45,6 +45,7 @@ v 8.13.0 (unreleased)
   - Changed Slack service user referencing from full name to username (Sebastian Poxhofer) 
 
 v 8.12.4 (unreleased)
+  - Fix issues importing services via Import/Export
   - Fix "Copy to clipboard" tooltip to say "Copied!" when clipboard button is clicked. (lukehowell)
 
 v 8.12.3

app/models/service.rb

@@ -136,6 +136,7 @@ class Service < ActiveRecord::Base
         end
 
         def #{arg}=(value)
+          self.properties ||= {}
           updated_properties['#{arg}'] = #{arg} unless #{arg}_changed?
           self.properties['#{arg}'] = value
         end

spec/models/service_spec.rb

@@ -203,6 +203,23 @@ describe Service, models: true do
     end
   end
 
+  describe 'initialize service with no properties' do
+    let(:service) do
+      GitlabIssueTrackerService.create(
+        project: create(:project),
+        title: 'random title'
+      )
+    end
+
+    it 'does not raise error' do
+      expect { service }.not_to raise_error
+    end
+
+    it 'creates the properties' do
+      expect(service.properties).to eq({ "title" => "random title" })
+    end
+  end
+
   describe "callbacks" do
     let(:project) { create(:project) }
     let!(:service) do