Do prefix search on incidents because its about prefix. ;)
Autocomplete should never be empty.

GET /autocomplete/?format=api
HTTP 200 OK
Allow: GET, HEAD, OPTIONS
Content-Type: application/json
Vary: Accept

[
    {
        "option": "Kopf"
    },
    {
        "option": "Boden"
    },
    {
        "option": "Person"
    },
    {
        "option": "Gesicht"
    },
    {
        "option": "Parolen"
    },
    {
        "option": "Angriff"
    },
    {
        "option": "Neonazis"
    },
    {
        "option": "Hakenkreuz"
    },
    {
        "option": "Hitlergruß"
    },
    {
        "option": "Körperverletzung"
    }
]