correct a logical error that would lead to merging unrelated preformatted blocks

gem300.rkt

@@ -41,7 +41,6 @@
 
           ;; add line to most recent preformat block
           [(symbol=? 'preformatted state)
-           (if (preformatted? (car document))
            ;; little bit hard to follow: take the existing
            ;; preformatted blocks content, cons the new line;
            ;; then, cons the new preformatted block to the cdr of
@@ -50,11 +49,7 @@
                                            (preformatted-str (car document))))
                        (cdr document))
                  (cdr lines)
-                     'preformatted)
-
-               (iter (cons (preformatted (list)) document)
-                     (cdr lines)
-                     'preformatted))]
+                 'preformatted)]
 
           ;; rest of this is normal mode
 
@@ -68,7 +63,7 @@
           ;; preformatting toggle lines
           [(string-prefix? (car lines) "```")
            ;; add preformatted block to document and toggle mode
-           (iter document
+           (iter (cons (preformatted (list)) document)
                  (cdr lines)
                  'preformatted)]