[fix] Crash when exporting notes (#5677)

Fixes https://github.com/koreader/koreader/issues/5609

plugins/evernote.koplugin/clip.lua

@@ -287,7 +287,7 @@ function MyClipping:parseHistoryFile(clippings, history_file, doc_file)
             title = title,
             author = author,
         }
-        self:parseHighlight(stored.highlight, stored.bookmarks, clippings.title)
+        self:parseHighlight(stored.highlight, stored.bookmarks, clippings[title])
     end
 end
 
@@ -318,7 +318,7 @@ function MyClipping:parseCurrentDoc(view)
         title = title,
         author = author,
     }
-    self:parseHighlight(view.highlight.saved, view.ui.bookmark.bookmarks, clippings.title)
+    self:parseHighlight(view.highlight.saved, view.ui.bookmark.bookmarks, clippings[title])
 
     return clippings
 end