Fix empty string custom action resulting in internal error

https://appsignal.com/openproject-gmbh/sites/673c8d4183eb67dcd6c4e764/exceptions/incidents/1037/samples/673c8d4183eb67dcd6c4e764-909226446337628072917766676802

https://community.openproject.org/wp/74131

app/models/custom_actions/actions/base.rb

@@ -46,7 +46,7 @@ class CustomActions::Actions::Base
   end
 
   def value_objects
-    values.map do |value|
+    values.filter_map do |value|
       allowed_values.find { |v| v[:value] == value }
     end
   end

spec/models/custom_actions/shared_expectations.rb

@@ -140,6 +140,15 @@ RSpec.shared_examples_for "associated custom action" do
       end
     end
 
+    describe "#value_objects" do
+      it "does not include nil for values not present in allowed_values" do
+        instance.values = [""]
+
+        expect(instance.value_objects)
+          .not_to include(nil)
+      end
+    end
+
     it_behaves_like "associated custom action validations"
   end
 end