fix bug

@@ -282,8 +282,11 @@ class DocView(GenericView, DocHandler):
         pdf_file = args.get('pdf_file')
         pdf_file = args.get('pdf_file')
         file_write(pdf_file, tmp_save_path)
         file_write(pdf_file, tmp_save_path)
 
 
-        # if not fitz.open("pdf", pdf_file).isPDF:
+        try:
             file = fitz.Document(tmp_save_path)
             file = fitz.Document(tmp_save_path)
+        except Exception as e:
+            raise self.invalid_params(msg='invalid params: not a PDF file')
+        else:
             if not file.isPDF:
             if not file.isPDF:
                 file.close()
                 file.close()
                 raise self.invalid_params(msg='invalid params: not a PDF file')
                 raise self.invalid_params(msg='invalid params: not a PDF file')