add special case for empty paragraphs

gem300.rkt

@@ -149,10 +149,14 @@
                       (inner-iter (list) rst)])
           (outer-iter (append acc (list inner-acc)) inner-rst))))
 
+  ;; the algorithm implemented here does not work for empty
+  ;; paragraphs. thus, they are handled as a special case here.
+  (if (non-empty-string? paragraph)
       ;; join each sublist into one string, and display one string per
       ;; line
       (for-each displayln
-            (map string-join (outer-iter (list) (string-split paragraph)))))
+                (map string-join (outer-iter (list) (string-split paragraph))))
+      (newline)))
 
 (define (render-gemtext document)
   (for-each (λ (line)