fix: undefined method 'zero?' for nil:NilClass (#8689)

app/services/action_service.rb

@@ -49,8 +49,10 @@ class ActionService
   end
 
   def assign_team(team_ids = [])
-    return unassign_team if team_ids[0].zero?
+    return unassign_team if team_ids[0]&.zero?
-    return unless team_belongs_to_account?(team_ids)
+    # check if team belongs to account only if team_id is present
+    # if team_id is nil, then it means that the team is being unassigned
+    return unless !team_ids[0].nil? && team_belongs_to_account?(team_ids)
 
     @conversation.update!(team_id: team_ids[0])
   end

spec/services/action_service_spec.rb

@@ -39,5 +39,10 @@ describe ActionService do
       action_service.assign_agent(['nil'])
       expect(conversation.reload.assignee).to be_nil
     end
+
+    it 'unassigns the team if team_id is nil' do
+      action_service.assign_team([nil])
+      expect(conversation.reload.team).to be_nil
+    end
   end
 end