Safer check for NAs in tiledb_config()

Replace `if(is.na())` as R 4.2 errors when conditions > 1L
Instead, removes NAs from `config`
Then, checks the length of `config`; if there is a length, adds it to
the TileDB config

fixes #518

R/Config.R

@@ -55,7 +55,8 @@ tiledb_config.from_ptr <- function(ptr) {
 #' @importFrom methods new
 #' @export tiledb_config
 tiledb_config <- function(config = NA_character_) {
-  if (!is.na(config)) {
+  config <- config[!is.na(x = config)]
+  if (length(x = config)) {
     stopifnot(`If given, the 'config' argument must be a name, value character vector` = is.character(config) && !is.null(names(config)))
     ptr <- libtiledb_config(config)
   } else {