Trying to get property of non-object in yii widget - php

Question

I faced with error
Trying to get property of non-object
The error disappears when I use my own widget. Here is the code of this widget
class OtherProductionWidget extends CmsWidget
{
public $category;
public $product;
public function init()
{
if(!$this->category)
return false;
$models = Product::getOtherProducts($this->category,$this->product);
if($models)
$this->render('view',array('models'=>$models));
}
}
The message of error indicates that I have problem in this line:
$this->render('view',array('models'=>$models));
The $models variable is not empty - I cheked it.
Here is which I use this widget:
<?php $this->widget('application.widgets.otherProductionWidget.OtherProductionWidget',array('category'=>$model->category_id,'product'=>$model->id));?>
The $model variable also not empty.
Tell me pleas what I doing wrong?
Here is a view part of widget:
<?php foreach($models as $model):?>
<a class="product dib"
href="<?php echo $model->link?>"
style="z-index: 6">
<span class="dib product-data pos-absolute text-align-justify">
<span class="text dib"><?php echo $model->name?></span><span class="dib image">
<img alt="<?php echo $model->link?>" class="dib thumb"
src="<?php echo $model->getImage(160,160,false)?>"
title="<?php echo $model->link?>">
</span><span class="dib width100 pos-relative row-fluid">
<span class="details">
<span class="dib details-inner"><?php echo Translation::t('More');?></span>
</span>
</span>
</span>
</a>
<?php endforeach?>