Fix in Subset.

R/Subset.R

@@ -80,6 +80,10 @@ Subset <- function(x, along, indices, drop = FALSE) {
       names(metadata[['dim']]) <- dim_names[-dims_to_drop]
       metadata[['dimensions']] <- dim_names[-dims_to_drop]
     }
+    if (length(metadata[['dim']]) == 0) {
+      metadata['dim'] <- list(NULL)
+      metadata['dimensions'] <- list(NULL)
+    }
   } else if (is.character(dim_names)) {
     names(metadata[['dim']]) <- dim_names
     metadata[['dimensions']] <- dim_names