PDF Output: Ignore links whose page refs cannot be found, instead of erroring out

src/calibre/ebooks/pdf/render/links.py

@@ -44,7 +44,11 @@ class Links(object):
         for link in links:
             href, page, rect = link
             p, frag = href.partition('#')[0::2]
+            try:
                 link = ((path, p, frag or None), self.pdf.get_pageref(page).obj, Array(rect))
+            except IndexError:
+                self.log.warn('Unable to find page for link: %r, ignoring it' % link)
+                continue
             self.links.append(link)
 
     def add_links(self):