# Get all files in the directory
 files <- list.files(outputs_dir, full.names = FALSE, recursive = TRUE)
+if (length(files) == 0) {
+  return(list())
+}
+
+# Filter to only files (not directories)
+full_paths <- file.path(outputs_dir, files)
+is_file <- !dir.exists(full_paths)
+files <- files[is_file]
+
 if (length(files) == 0) {
   return(list())
 }
 
 # Create PMData objects using lapply
 file_ids <- gsub("\\", "/", tools::file_path_sans_ext(files), fixed = TRUE)
 file_paths <- normalizePath(file.path(outputs_dir, files), mustWork = FALSE)
 
 lapply(seq_along(files), function(i) {
   PMData$new(id = file_ids[i], path = file_paths[i])
 })

 write = function(x, ...) {
+  # Stop if path is an existing directory
+  if (dir.exists(self$path)) {
+    stop("Cannot write to a path that is an existing directory: ", self$path, call. = FALSE)
+  }
+
   # Create the folder in case it doesn't exist
   dir.create(dirname(self$path), showWarnings = FALSE, recursive = TRUE)
 
   # For RData files, we need   to preserve object names from the original call
   ext <- tolower(tools::file_ext(self$path))
   if (ext %in% c("rdata", "rda")) {
     # ...
   } else {
     # Call pm_write_file for other file types
     pm_write_file(self$path, x, ...)
   }
   invisible(self)
 }