Improve some error handling. Closes #150

providers/callsigndata/qrz.py

@@ -1,6 +1,7 @@
 import logging
 import urllib.parse
 from datetime import datetime, timedelta
+from xml.parsers.expat import ExpatError
 
 import pytz
 import xmltodict
@@ -56,6 +57,9 @@ class QRZ(APIQueryCallsignDataProvider):
                         # Log this failure at debug level only, not our problem if user entered the wrong password.
                         logger.debug("QRZ.com login details incorrect, failed to look up with QRZ.")
                         return None
+                except ExpatError:
+                    logger.warning("QRZ.com provided blank or malformed content when trying to authenticate")
+                    return None
                 except Exception:
                     logger.exception("Exception when getting QRZ.com session key")
                     return None