TypeError: Cannot read property 'replace' of undefined (row 84).

[Obi-Five]

Hi,
Sorry but i don't know jawascript so i don't know how to try to fix it by myself.
I am trying to read this data and I get the error code present in the subject of the message.

{
"id": 8870,
"whitelisted": false,
"buys": {
"quantity": 21843,
"unit_price": 128
},
"sells": {
"quantity": 45074,
"unit_price": 166
}
}

Thanks for the support!