Hey. It's because your old config had this in pumpjack gather
"lowgradefuel": {
"Output Item - Shortname": "diesel_barrel",
"Output Item - Skin": 3205339144,
"Output Item - Display Name": "Nuclear Fuel",
"Output Item - Icon URL (Required if Skin not 0)": "",
"Include Always": false,
"Required Permission (empty if not required)": "",
"Chance": 25,
"Minimal Output Per Tick": 0.8,
"Maximal Output Per Tick": 22.0,
"Additional Items Required To Place": []
}
And on new one it's missing, that's why it prints errors.