task_fix.diff

diff --git a/app/business_logic/services/broadband_provider_actions/backends/task.rb b/app/business_logic/services/broadband_provider_actions/backends/task.rb
index c6968d9..726e40e 100644
--- a/app/business_logic/services/broadband_provider_actions/backends/task.rb
+++ b/app/business_logic/services/broadband_provider_actions/backends/task.rb
@@ -26,7 +26,7 @@ module Services
         def undo
           original_command = track_back_object.command.sub('Undo', '')
           original_action = track_back_object.event.actions.find_by(command: original_command)
-          task = original_action.result
+          task = original_action.try(:result)
           return unless task
           Interactors::Tasks::Cancel.new(id: task.id, track_back_object: track_back_object).perform
         end
diff --git a/spec/business_logic/services/broadband_provider_actions/backends/task_spec.rb b/spec/business_logic/services/broadband_provider_actions/backends/task_spec.rb
index c052789..8f190a7 100644
--- a/spec/business_logic/services/broadband_provider_actions/backends/task_spec.rb
+++ b/spec/business_logic/services/broadband_provider_actions/backends/task_spec.rb
@@ -46,6 +46,12 @@ describe Services::BroadbandProviderActions::Backends::Task do
     And{expect(task.task_type).to eq expected_task_type}
   end
 
+  shared_examples_for "undo action with no result on the event" do
+    Given!(:previous_action){nil}
+    When{subject.undo}
+    Then{expect(task).to be_nil}
+  end
+
   describe "#perform" do
     Given(:task){Task.last}
 
@@ -76,6 +82,10 @@ describe Services::BroadbandProviderActions::Backends::Task do
         Then{expect(result).to_not have_failed}
         And{expect(Task.count).to be_zero}
       end
+
+      context "with an undo action and no previous task is found" do
+        include_examples "undo action with no result on the event"
+      end
     end
 
     context "cancel" do