I am getting undefined offset:0 Error in Category, subcategory, Subsub category page

I am trying to display category, subcategory, subsubcategory page but i am getting undefined offset:0 error when i am opening any page. Please let me know how i can show my data on a perticular page.

here is my controller GuidePagesController.php

 public function categoryGuides(Request $r, $cat, $subcat=NULL, 
  $subsubcat=NULL){
 $guidedata=GuidePages::all();
 if($cat != NULL && $subcat != NULL && $subsubcat != NULL){

$cat = Category::where('slug',$cat)->get();
$subcatid = Subcategory::where('slug',$subcat)->get();
$subsubcatid = SubSubcategory::where('slug',$subsubcat)->get();
$guides = GuidePages::where(function($q) use($cat, $subcatid, 
$subsubcatid)
{
 $q->where('category_id','=', $cat[0]->id)
->where('subcategory_id','=', $subcatid[0]->id) 
 ->where('subsubcategory_id','=', $subsubcatid[0]->id);       
 })->orderBy('id','desc')->paginate(8);
 }
elseif($cat != NULL && $subcat != NULL){
$cat = Category::where('slug',$cat)->get();
$subcatid = Subcategory::where('slug',$subcat)->get();
 $guides = GuidePages::where(function($q) use($cat, $subcatid){
 $q->where('category_id','=', $cat[0]->id)
 ->where('subcategory_id','=', $subcatid[0]->id);       
})->orderBy('id','desc')->paginate(8);
}
else{
$cat = Category::where('slug',$cat)->get();
 $guides = GuidePages::where('category_id','=', $cat[0]->id)- 
 >orderBy('id','desc')->paginate(10);
 }

$data=['guidedata'=>$guidedata,'guides'=>$guides,'cat'=>$cat[0]- 
 >category_name,];
  return view('guide-pages', $data);

   }

And here is my route:

Route::get("category/{cat}/{subcat?}/{subsubcat?}", ["uses" => "GuidePagesController@categoryGuides", "as" => "category.cat.product"]);

via Chebli Mohamed