Errorr Returnn value of Maatwebsite\Excel\Sheet::mapArraybleRow() must be of the type array, string returned

I just upgraded Laravel 5.4 to 5.5 and now I have to change all the coding that used the old Laravel-Excel.

I'm using php 7.2.25, Windows/Wamp.

I am trying to upload an excel file, get it's data, do lots of check and calculations on it (Not in the code yet) and then create a new excel file and give the user the Windows 'Save File' option.

1. Not sure how to get the Windows save file window, don't see any explanation on the documentation.

1.1 If I can't get the Windows save file window, I'm not sure how to set the path to: My Documents\test for example.

2. With the code I have, I get this error:

Symfony \ Component \ Debug \ Exception \ FatalThrowableError (E_RECOVERABLE_ERROR) Type error: Return value of Maatwebsite\Excel\Sheet::mapArraybleRow() must be of the type array, string returned

My Import class code:

namespace App\Imports;

use Illuminate\Support\Collection;
use Maatwebsite\Excel\Concerns\ToCollection;
use App\Exports\TimesheetsExport;
use Maatwebsite\Excel\Concerns\WithHeadingRow;
use Maatwebsite\Excel\Facades\Excel; 
use App\User;

class TimesheetsImport implements ToCollection, WithHeadingRow
{
private $user;

public function __construct($param)
{
    $this->user = $param;
}

public function collection(Collection $rows)
{
    $data = new Collection([$this->user->fullName()]);
    foreach ($rows as $row) 
    {
        $data->put($row['date'], $row['in'], $row['out']);
    }

return Excel::download(new TimesheetsExport($data), 'testtttt.xlsx');

My Export class:

namespace App\Exports;

use Maatwebsite\Excel\Concerns\FromCollection;
use Illuminate\Support\Collection;

class TimesheetsExport implements FromCollection
{
    protected $rows;

    public function __construct(Collection $rows)
    {
        $this->rows = $rows;
    }

    public function collection()
    {
        return $this->rows;
    }
}

Can someone please help?

via Chebli Mohamed