error msg for no pages

6 years ago · d1c8b93f7b
parent 85dee608ce
commit d1c8b93f7b
1 changed files with 4 additions and 1 deletions
--- a/pitfall/pitfall/page.rkt
+++ b/pitfall/pitfall/page.rkt
@ -8,7 +8,10 @@

 (provide (all-defined-out))

-(define (current-page doc) (car (pdf-pages doc)))
+(define (current-page doc)
+  (match (pdf-pages doc)
+    [(? pair? ps) (car ps)]
+    [_ (raise-argument-error 'current-page "no pages in pdf" doc)]))

 (define (add-content doc data)
  (page-write (current-page doc) data))