Check projpred version for latent projection

NEWS.md

@@ -10,8 +10,8 @@ via the `hurdle_cumulative` family thanks to Stephen Wild. (#1448)
 in post-processing methods that require a compiled Stan model.
 * Extend control over the `point_estimate` feature in `prepare_predictions`
 via the new argument `ndraws_point_estimate`.
-* Add support for the latent projection available in **projpred** versions >
-2.3.0.
+* Add support for the latent projection available in **projpred** versions >=
+2.4.0.
 
 ### Bug Fixes
 

R/projpred.R

@@ -17,7 +17,8 @@
 #'   \code{\link[projpred:init_refmodel]{init_refmodel}}, but leave this at
 #'   \code{NULL} unless \pkg{projpred} complains about it.
 #' @param latent See argument \code{latent} of
-#'   \code{\link[projpred:extend_family]{extend_family}}.
+#'   \code{\link[projpred:extend_family]{extend_family}}. Setting this to
+#'   \code{TRUE} requires a \pkg{projpred} version >= 2.4.0.
 #' @param brms_seed A seed used to infer seeds for \code{\link{kfold.brmsfit}}
 #'   and for sampling group-level effects for new levels (in multilevel models).
 #' @param ... Further arguments passed to
@@ -206,6 +207,7 @@ get_refmodel.brmsfit <- function(object, newdata = NULL, resp = NULL,
       )
     }
   } else if (latent) {
+    require_package("projpred", "2.4.0")
     if (family$family == "cumulative") {
       args$latent_ilink <- latent_ilink_cumulative(
         object = object, family = family, bterms = bterms, resp = resp