Simple store validation Request don't return error just redirect to form view with 302 error

I don't understand why Laravel don't send me validation error and redirects me to the view with 302 error.

I just have simple forms in the view which just send this :

            @else
                        
                        <div class="md-form input-group">
                            <input type="hidden" name="route_name" value="">
                            <input type="hidden" name="href" value="">
                            <input pattern="[a-zA-Zéè \-]{3,35}" required class="form-control" type="text" name="title"
                                   id="linkTitle"
                                   value=""
                                   placeholder="Ajoutez ici un titre à ce lien pour le rendre disponibles pour les menus">
                            <span class="input-group-btn">
                             <button type="button"
                                     class="btn btn-default ml-2 btnUpdateLink">Ajouter</button>
                        </span>

                            
                        </div>
                    @endif

the forms sends data to my store method :

            public function store(LinkRequest $request)
                {

                    //dd($request->all());

                    try{

                        Link::create($request->all());
                        return redirect(route('Permission.index'))->with('success-message','Lien crée');

                    }catch (Exception $e){
                        $errorCode = $e->errorInfo[1];
                        dd($errorCode);
                        if($errorCode == 1062){
                            return redirect(route('Link.index'))
                                ->with('error_message','Un lien existe déjà avec ce titre')
                                ->with('create_name',$request->get('title'));
                        }
                    }

                }

and here is my LinkRequest class :

                public function rules()
                {
                    return [
                        'title'=> array(
                            'required',
                            'max:35',
                            'unique:links,title,'.$this->Link,
                            'regex:[a-zA-Zéè]',
                        ),
                        'route_name'=>array(
                            'required'
                        ),
                        'href'=>array(
                            'required'
                        ),

                    ];
                }

Thanks for your help !

via Chebli Mohamed