Livewire - Call to a member function getClientOriginalExtension() on string - laravel

Question

I get a error from livewire file uploading "Call to a member function getClientOriginalExtension() on string" Please help me any why I get the problem from livewire controller functions. I attached livewire form and controller function codes.
<div class="mb-3 col-xl-8">
<div class="card">
<div class="card-body">
<form wire:submit.prevent="RegisterNewUserAdmin">
<div class="row">
<div class="col-lg-1">
<select class="form-control" wire:model.prevent="RegisterUserMethods">
<option value="" selected>Select</option>
<option value="manually">Manually</option>
<option value="fromXLSfile">From XLS File</option>
</select>
</div>
<div class="col-lg-3">
<input type="text" wire:model="newusername" class="form-control" placeholder="Write User Full Name" required>
</div>
<div class="col-lg-3">
<input type="email" wire:model="newuseremail" class="form-control" placeholder="Write Email ID" required>
</div>
<div class="col-lg-3">
<input type="password" wire:model="newuserpassword" class="form-control" placeholder="Password" required>
</div>
<div class="col-lg-9">
<input type="file" wire:model="NewUserxlsFile" class="form-control" required>
</div>
<div class="col-lg-2">
<button type="submit" class="btn btn-success w-100"><div wire:loading wire:target="RegisterNewUserAdmin" class="spinner-border"></div> Add Now</button>
</div>
</div>
</form>
</div>
</div>
</div>
Controller Function
public function RegisterNewUserAdmin()
{
$str = Str::random(10);
$file = $this->NewUserxlsFile;
$filename = $str.'.'.$file->getClientOriginalExtension();
$path = $this->NewUserxlsFile->storeAs('files/xls/', $filename, 'public');
$data = Excel::load($path)->get();
dd($data);
}