Hey all I am receiving the following error

Error: Array.prototype.sort() expects a value to be returned at the end of arrow function  array-callback-return

the code that is causing this error is below

filteredData.sort((a, b) => {
    if (a.distance !== undefined) {
        let aValue = parseFloat(a.distance.split(' mi')[0])
        let bValue = parseFloat(b.distance.split(' mi')[0])
        if (aValue !== undefined && bValue !== undefined) {
            return aValue > bValue ? 1 : -1
        }
    } else {
        return 1
    }
})

Can anyone tell me what I am doing wrong ?