Fix #1838 (Log message on failed OPDS login)

cps/helper.py

@@ -32,7 +32,7 @@ from tempfile import gettempdir
 import requests
 from babel.dates import format_datetime
 from babel.units import format_unit
-from flask import send_from_directory, make_response, redirect, abort, url_for
+from flask import send_from_directory, make_response, redirect, abort, url_for, request
 from flask_babel import gettext as _
 from flask_login import current_user
 from sqlalchemy.sql.expression import true, false, and_, text
@@ -68,6 +68,7 @@ try:
 except (ImportError, RuntimeError) as e:
     log.debug('Cannot import Image, generating covers from non jpg files will not work: %s', e)
     use_IM = False
+    MissingDelegateError = BaseException
 
 
 # Convert existing book entry to new format