What happens if you try to run a MWSE compiled script without MWSE installed?

I am working on a mod which needs to stop the player carrying anything through a tunnel, no armor, no weapons, nothing. The xGetEncumb function seems perfect. I assume it works on the player and is not affected by the feather spell effect (maybe it is?). If I do use it in my script, will it run and just ignore the command, or will it crash. Do I have to make two scripts, one for MWSE, one for vanilla, or can you detect if MWSE is running and jump over the MWSE specific code. I am running MGSO which has an old version of MWSE, but I don't want to uninstall MGSO just to test what happens. I also haven't tried to compile any MWSE scripts, so if this is a dumb question, my apologees.

If someone knows a non-MWSE way to check if the player is carrying nothing, please let me know.