DET warning adds two warnings to the feild desginer to prevent accidently breaking DET code. The EM also allows the end user to browse the DET's code.
This EM isn't yet available to install via redcap's EM database so you'll need to install to your modules folder (i.e. redcap/modules/det_warning_v1.0.0) manually.
No configuration is required, other than setting a DET at the project level, for this EM.