Laravel Uploading image post

Hi Everyone !

I must submit post's informations and featured image (path) to the database via a form.

Here, my code works better but sometimes users will not be obliged to attach an image to the post.

So, when i submit informations with an empty image field, i got errors.

The question is How can i do to submit a form with an empty image field without catching errors.

Thanks for your help !

Codes :

Form in my view :

                {!! csrf_field() !!}

Title

                    <input id="Title" type="text" class="form-control" name="Title">

Text

                    <textarea id="ckeditor" class="ckeditor" name="Content"></textarea>
                    <script type="text/javascript">

                        CKEDITOR.replace('ckeditor');

                    </script> 

Categorie :

                            <select id="IdCat" class="form-control" name="IdCat">

                                <?php
                                foreach ($cat as $cats) {
                                    ?>

                                    <option value="<?php echo $cats->IdCat ?>"><?php echo $cats->NomCat ?></option>

                                    <?php
                                }
                                ?>


                            </select>


                            <label for="ImagePlan" class="control-label">Featured image : </label>
                            <input type="file" id="ImagePlan" name="ImagePlan" class="control-label">

                            <button type="submit" class="btn btn-primary">
                                <i class="fa fa-btn alert-success"></i> Publier
                            </button>

        </form>

Method in my controller named PostController :

public function insertPost(Request $req) {

   $post= new Post;
 
   $post->IdCat=$req->IdCat;
   $post->Title=$req->Title;
   $post->User_Id=$req->User_Id;
   $post->Content=$req->Content;

   $image=$req->file('ImagePlan');
   $filename=$image->getClientOriginalName();

   Storage::disk('uploads')->put('/imagesPost/'.$filename,file_get_contents($req->file('ImagePlan')->getRealPath()));
 
   $post->ImagePlan=$filename;
   
   $post->save();

   session()->flash('success','Operation succeed');
   return redirect()->route('admin');

}

This is the error :

FatalErrorException in PostController.php line 30: Call to a member function getClientOriginalName() on a non-object