Attempt to read property "name" on null

Model category

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;

class Katagori extends Model
{
    use HasFactory;
    protected $fillable = ['name','slug'];

    public function post()
    {
        return $this->hasMany(Post::class);
    }
}

model post

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;

class Post extends Model
{
    use HasFactory;
    protected $fillable=[
        'seotitle',
        'keyword',
        'deskripsi',
        'title',
        'slug',
        'body',
      'user_id',
      'category_id',
        'thumbnail'
    ];

    public function tag()
    {
        return $this->belongsToMany(Tag::class);
    }

    public function katagori()
    {
        return $this->belongsTo(katagori::class);
    }

    public function user()
    {
        return $this->belongsTo(User::class);
    }

    public function getPictureAttribute()
    {
        return asset ('storage/'. $this->thumbnail);
    }
   

    public function comments()
    {
        return $this->morphMany(Comment::class, 'commentable')->whereNull('parent_id');
    }
}

controller

<?php

namespace App\Http\Controllers;

use App\Models\Tag;


use App\Models\Menu;
use App\Models\Post;

use App\Models\Team;
use App\Models\Rating;
use App\Models\Partner;
use App\Models\Katagori;
use App\Models\Portfolio;
use App\Models\InsertHeader;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\DB;

class BerandaController extends Controller
{
    /**
     * Display a listing of the resource.
     *
     * @return \Illuminate\Http\Response
     */
    public function index()
    {
        return view('welcome',[
            'post' => Post::paginate(2),
            'team' => Team::paginate(4),
            'portofolio' => Portfolio::get(),
            'partner' => Partner::get(),
            'rating' => Rating::get(),
            'info' => InsertHeader::paginate(1),
        ]);
    }

    public function about()
    {
        return view('home.about',[
            
           
           
        ]);
    }
    
      public function faq()
    {
        return view('home.faq',[
            
           
           
        ]);
    }
    
       public function lisensi()
    {
        return view('home.lisensi',[
            
           
           
        ]);
    }
    
    
    
    
    
    
    
    public function service()
    {
        return view('home.service',[
            
            'portofolio' => Portfolio::get(),
           
        ]);
    }




    public function porto()
    {
        return view('home.portofolio',[
            
            'portofolio' => Portfolio::all(),
           
        ]);
    }
    public function portof($slug)
    {
        
    	return view('home.portofoliodetail', [
           
    	    'portofolio' => Portfolio::where('slug', $slug)->get(),
        ]);
    }

    public function logo()
    {
       
        $logo = DB::table('Logos')->get();
        return view('layouts.app',[
            'logo' => $logo,
            
            ] );
    }

    

    public function blog()
    {
        return view('home.blog',[
            
            'post' =>  Post::latest()->paginate(6),
            'katagori' => Katagori::all(),
            'tag' => Tag::all(),
        ]);

    }
    
    
    // public function katagori(katagori $katagori){
    //     $katagori = Katagori::all();

    //     $data = $Katagori->post()->paginate(6);
    //     return view('home.blog', compact('data','katagori'));
    // }
    
    

    public function artikel($slug)
    {
        
    	return view('home.blogdetail', [
           
            'katagori' => katagori::all(),
            'tag' => Tag::all(),
    	    'post' => Post::where('slug', $slug)->get(),
        ]);
    }
    /**
     * Show the form for creating a new resource.
     *
     * @return \Illuminate\Http\Response
     */
    public function create()
    {
        //
    }

    /**
     * Store a newly created resource in storage.
     *
     * @param  \Illuminate\Http\Request  $request
     * @return \Illuminate\Http\Response
     */
    public function store(Request $request)
    {
        //
    }

    /**
     * Display the specified resource.
     *
     * @param  int  $id
     * @return \Illuminate\Http\Response
     */
    public function show($id)
    {
        //
    }

    /**
     * Show the form for editing the specified resource.
     *
     * @param  int  $id
     * @return \Illuminate\Http\Response
     */
    public function edit($id)
    {
        //
    }

    /**
     * Update the specified resource in storage.
     *
     * @param  \Illuminate\Http\Request  $request
     * @param  int  $id
     * @return \Illuminate\Http\Response
     */
    public function update(Request $request, $id)
    {
        //
    }

    /**
     * Remove the specified resource from storage.
     *
     * @param  int  $id
     * @return \Illuminate\Http\Response
     */
    public function destroy($id)
    {
        //
    }



    public function website()
    {
        return view('home.layananwebsite',[
            
            'portofolio' => Portfolio::paginate(6),
           
        ]);
    }

    public function digital()
    {
        return view('home.digitalmarketing',[
            
            'portofolio' => Portfolio::paginate(6),
           
        ]);
    }

    public function seo()
    {
        return view('home.seo',[
            
            'portofolio' => Portfolio::paginate(6),
           
        ]);
    }

    public function maintenance()
    {
        return view('home.maintenance',[
            
            'portofolio' => Portfolio::paginate(6),
           
        ]);
    }
    public function program()
    {
        return view('home.program',[
            
            'portofolio' => Portfolio::paginate(6),
           
        ]);
    }

    public function ads()
    {
        return view('home.ads',[
            
            'portofolio' => Portfolio::paginate(6),
           
        ]);
    }
  
}