Passing HTML back inside a JSON object
I would consider returning with a more detailed JSON object:

{
    errorMessage: "things have gone wrong!",
    data: [
        {
            link: #,
            linkText: Test,
            size: 0MB
        },
        {
            link: #,
            linkText: Test2,
            size: 1MB
        }
}


It moves some processing from the server to the clients but it's more reusable. For example you need a second type of table later with the same data but with an extra column. With this JSON format you don't have to touch the server side code nor to parse and modify the returned HTML on the client side.

Finally, if there is an error maybe you want to omit the whole data part:

{
    errorMessage: "things have gone wrong!",
}