small fix

src/access.py

@@ -40,7 +40,7 @@ class Access:
             params = json.load(f)
 
         self.refreshing.clear()
-        self.url = url or params['url']
+        self.url = url
         self.username = params['username']
         self.password = params['password']
         self.refreshing.set()

src/consumer.py

@@ -47,10 +47,11 @@ def callback(ch, method, properties, body, logger):
     logger.info(f'Message: {body}.')
     try:
         data = json.loads(body)
-        api_url = data['apiURL'] if 'apiURL' in data else None
+        assert 'apiURL' in data, 'No apiURL field in received message.'
+
         params = {
             'book_id': data['id'],
-            'access': Access(url=api_url),
+            'access': Access(url=data['apiURL']),
             'logger': logger
         }