count array = 0

[havantuan]

$first_row = $this->data->first();
foreach ($first_row as $item) {
if (!is_string($item)) {
$need_conversion = true;
}
}
Check $first_row not null and foreach.

[rap2hpoutre]

Thank you for your contribution! Feel free to submit a PR if you want to fix it (or I can do it myself, as you want!)

[havantuan]

Excel found unreadable content in file excel. Do you want to recover the contents of the this workbook.
Why I choose yes, then press no I can open file.

[rap2hpoutre]

Fixed in v0.3.2. Update your dependencies to this version to make it work with empty things.