[fix] encapsulate wolframalpha token fetching errors

searx/engines/wolframalpha_noapi.py

@@ -44,9 +44,12 @@ token = {'value': '',
 # seems, wolframalpha resets its token in every hour
 def obtain_token():
     update_time = time() - (time() % 3600)
+    try:
         token_response = http_get('https://www.wolframalpha.com/input/api/v1/code?ts=9999999999999999999', timeout=2.0)
         token['value'] = loads(token_response.text)['code']
         token['last_updated'] = update_time
+    except:
+        pass
     return token