Leaflet: Leaflet tries to get negative value images or images that don't exist

Here is my Leaflet config:

function init() {
    var mapMinZoom = 2;
    var mapMaxZoom = 5;
    var map = L.map('map', {
        maxZoom: mapMaxZoom,
        minZoom: mapMinZoom,
        crs: L.CRS.Simple
    }).setView([0, 0], mapMaxZoom);

    var mapBounds = new L.LatLngBounds(
        map.unproject([0, 4352], mapMaxZoom),
        map.unproject([2048, 0], mapMaxZoom));

    map.fitBounds(mapBounds);
    L.tileLayer('/assets/themes/sec/img/tiles/{z}/{x}/{y}.png', {
        minZoom: mapMinZoom,
        maxZoom: mapMaxZoom,
        bounds: mapBounds,
        noWrap: true,
        continuousWorld: true
    }).addTo(map);

    var store_marker = L.marker([0, 0]).addTo(map);
}

Everything works, but I get a lot of “resource not found” in my console whenever I zoom or pan:

[Error] Failed to load resource: the server responded with a status of 404 (Not Found) (0.png, line 0)
http://localhost:3000/assets/themes/sec/img/tiles/2/-1/0.png

[Error] Failed to load resource: the server responded with a status of 404 (Not Found) (0.png, line 0)
http://localhost:3000/assets/themes/sec/img/tiles/2/1/0.png

[Error] Failed to load resource: the server responded with a status of 404 (Not Found) (1.png, line 0)
http://localhost:3000/assets/themes/sec/img/tiles/2/-1/1.png

[Error] Failed to load resource: the server responded with a status of 404 (Not Found) (1.png, line 0)
http://localhost:3000/assets/themes/sec/img/tiles/2/1/1.png

I have no negative numbered tiles. The files referenced here don’t exist. Yet everything looks fine on the map. I used MapTiler to build the map. Anything I can do to fix this?