Recently we are transitioning from 2018 LTS to 2019 LTS. We have been creating custom packages a lot and have used NSubstitute for our tests. When updating to 2019 LTS, we ran into a problem, where the script wont compile. I think the main issue was that we had runtime tests, that uses NSubstitute and it seems to not be allowed in 2019 LTS. Is there any suggestion on how to fix this so we can upgrade to 2019 LTS? Or was it something that we have done wrongly on 2018, that tests should not be using NSubstitute in runtime?