attempt to close #238 (#242)

```
> library(rlistings)
Loading required package: formatters

Attaching package: ‘formatters’

The following object is masked from ‘package:base’:

    %||%

Loading required package: tibble
> result <- tibble::tibble(col1 = character(0L), col2 = character(0L), col3 = character(0L))
> 
> listing <- rlistings::as_listing(result)
> 
> sprintf("Rows: %d // Columns: %d", nrow(listing), ncol(listing))
[1] "Rows: 0 // Columns: 3"
> 
> print(listing)
[1] "No observation in the listing object."
```

---------

Signed-off-by: Joe Zhu <sha.joe.zhu@gmail.com>
Co-authored-by: André Veríssimo <211358+averissimo@users.noreply.github.com>

R/rlistings_methods.R

@@ -15,17 +15,25 @@ dflt_courier <- font_spec("Courier", 9, 1)
 #' @export
 #' @name listing_methods
 print.listing_df <- function(x, widths = NULL, tf_wrap = FALSE, max_width = NULL, fontspec = NULL, col_gap = 3L,  ...) {
-  cat(
-    toString(
-      matrix_form(x, fontspec = fontspec, col_gap = col_gap),
-      widths = widths,
-      tf_wrap = tf_wrap,
-      max_width = max_width,
-      fontspec = fontspec,
-      col_gap = col_gap,
-      ...
+  tryCatch({
+    cat(
+      toString(
+        matrix_form(x, fontspec = fontspec, col_gap = col_gap),
+        widths = widths,
+        tf_wrap = tf_wrap,
+        max_width = max_width,
+        fontspec = fontspec,
+        col_gap = col_gap,
+        ...
+      )
     )
-  )
+  }, error = function(e) {
+    if (nrow(x) == 0) {
+      print("No observation in the listing object.")
+    } else {
+      stop(e)
+    }
+  })
   invisible(x)
 }