Laravel Livewire image upload verification on edit form problem - php

Question

I have a product page with an image upload form built with Livewire. when i revisit the page to update information, the page will only submit if I also pass through a new image even if I update other fields. I want it to keep the current uploaded image if the image form isn't touched, allow me to update other fields without a new image upload, and upload and replace the image url when that section is updated.
I have tried all sorts of validator modifiers - nullable, sometimes, and a few if statements and i can't seem to figure it out.
Here is my upload function in my Livewire Component:
public function updateProductVariant($id)
{
$productVariant = ProductVariant::find($id);
$validated = $this->validate([
'img_url'=>'sometimes|image',
'available_end_date'=>'required',
'available_start_date'=>'required',
'notes'=>'required',
]);
$img_url = $productVariant->img_url;
if($validated['img_url'] != "")
{
$name = $productVariant->id . '.' . $validated['img_url']->extension();
$this->img_url->storeAs('public', $name);
$img_url = "/storage/$name";
}
$categories = ['Dough', 'Merch' , 'Packaging' , 'Supplies' , 'Kits' ,
'Featured' , 'Upcoming' , 'Clearance'];
foreach($categories as $category) {
if($this->$category) {
ProductCategory::updateOrCreate(['category_name'=>$category , 'product_variant_id'=>$id],[]);
} else {
ProductCategory::where('category_name' , $category)->where('product_variant_id' , $id)->delete();
}
}
ProductVariant::updateorCreate(
['id' => $id],
[
'img_url' => $img_url,
'available_end_date' => $validated['available_end_date'],
'available_start_date' => $validated['available_start_date'],
'notes' => $validated['notes'],
]);
session()->flash('message', 'Product successfully updated');
$this->resetFields();
$this->emit('gotoTop');
return redirect("corporate/cookies");
}
And my relevant blade section:
<!--/form-group-->
<div class="mb-3">
<input class="form-control form-control-lg" type="file" id="img_url" name="img_url" wire:model="img_url">
<br>
#if($img_url && !is_string($img_url))
<div style="text-align: center;"> <img src="{{$img_url->temporaryUrl()}}" alt="" class="img-fluid rounded-3" style="max-width: 50%;"></div>
#endif
<div style="text-align: center;"> <img src="{{ $img_url }}" alt="" class="img-fluid rounded-3" style="max-width: 50%;"></div>
</div>
<!--/extra-->
<br>
<div class="d-grid mb-">
<button type="submit" class="btn btn-lg btn-block btn-primary" wire:click.prevent="updateProductVariant({{$item_id}})">Update</button>
</div>