noll --> 0

conf.js

 var conf = {}
 conf.port = 9002;
 conf.items = [
-  {"display": "empty"       ,"exchange":{"Value":null, "Unit":"mbar"}}
+  {"display": "empty"       ,"exchange":{"Value":0, "Unit":"mbar"}}
 , {"display": "SRG"          ,"exchange":{"Value":2e-2, "Unit":"mbar"}}
 , {"display": "0.1T CDG"     ,"exchange":{"Value":0.133, "Unit":"mbar"}}
 , {"display": "0.25T CDG"    ,"exchange":{"Value":0.333, "Unit":"mbar"}}