Undefined array key but with dd() works

I've done a query at Laravel and to check result content, I've used dd, but, for some reason, when I remove the dd(), it throws an exception sayint "Undefined array key 0". However, with dd DO find the key.

Code is this:

public function getFormatosArticulo(Articulo $articulo){
    $formatoRaw = Formato::where('articulo_id', '=', $articulo->id)->get();
    dd($formatoRaw[0]);
    $formato = $formatoRaw[0];
    return $formato;
}

And dd output is this:

I guess you are calling getFormatosArticulo function for multiple times, and passed not exists id into it. The get() function will always return a empty collection even if no data matched.

Can you test your function use code below and check if id does exists or not?

public function getFormatosArticulo(Articulo $articulo){
    try {
        $formatoRaw = Formato::where('articulo_id', '=', $articulo->id)->get();
        $formato = $formatoRaw[0];
        return $formato;
    catch (Exception $e) {
        dd($articulo->id); // i guess there is no articulo_id equal this in formato table.
    }
}