model$intervals = NULL
doesn't error, but it does nothing (the interval requests remain)
model@intervals = NULL
fails with an error:
Error in checkAtAssignment("MxModel", "intervals", "NULL") :
assignment of an object of class “NULL” is not valid for @‘intervals’ in an object of class “MxModel”;
It would be nice if the $ operator allowed removing CI requests from models.
Currently (for reasonable reasons), adding a CI request doesn't step on the existing ones, so they just accumulate with no obvious way to remove potentially expensive but unwanted CI requests.