Update safaribooks.py

Try to fix lorenzodifuccia#244 and lorenzodifuccia#236

safaribooks.py

@@ -169,7 +169,7 @@ def parse_description(self, desc):
  return "n/d"
 
  def book_info(self, info):
- description = self.parse_description(info["description"]).replace("\n", " ")
+ description = self.parse_description(info.get("description", None)).replace("\n", " ")
  for t in [
  ("Title", info.get("title", "")), ("Authors", ", ".join(aut.get("name", "") for aut in info.get("authors", []))),
  ("Identifier", info.get("identifier", "")), ("ISBN", info.get("isbn", "")),
@@ -948,10 +948,10 @@ def create_content_opf(self):
  "media-type=\"text/css\" />".format(i))
 
  authors = "\n".join("<dc:creator opf:file-as=\"{0}\" opf:role=\"aut\">{0}</dc:creator>".format(
- escape(aut["name"])
- ) for aut in self.book_info["authors"])
+ escape(aut.get("name", "n/d")])
+ ) for aut in self.book_info.get("authors", []))
 
- subjects = "\n".join("<dc:subject>{0}</dc:subject>".format(escape(sub.get("name", "")))
+ subjects = "\n".join("<dc:subject>{0}</dc:subject>".format(escape(sub.get("name", "n/d")))
  for sub in self.book_info.get("subjects", []))
 
  return self.CONTENT_OPF.format(