You can try
export MARLIN_DEBUG=1
This keeps Marlin from unloading the libraries from MARLIN_DLL.
Then the error disappears for me.
Besides not printing a humongous error message, only the output
[ VERBOSE "UNKOWN"]
[ VERBOSE "UNKOWN"] <!-- MARLIN_DEBUG=1 set in your environment - skip unloading processors -->
appears at the end.
Or are the any adverse affects to not unloading the libraries I am not aware of?
Cheers,
Andre
PS: The main reason would be for automatic systems to not be thrown off by a non-zero exit status of Marlin.