Trying to get property of non-object - Laravel Form - forms

Question

I am creating a form with a many-many relationship. I have a posts table and an activities table. There is a many to many link using pivot table. I am creating a form to add one or more activities to the posts. I am receiving an 'ErrorException' - Trying to get property of non-object. I cannot understand why this is not working.
I would be grateful for any assistance you can offer me.
My relevant code is below.
//Posts/create.blade.php
{!!Form::open(['action' => 'PostController#store','method' => 'POST', 'class'=>'form-group'])!!}
{{Form::bsText('title','',['placeholder' => 'Trip Name'])}}
{{Form::bsTextarea('body','',['placeholder' => 'Trip Description'])}}
{{Form::bsSubmit('submit')}}
{{Form::label('activities', 'Activity:') }}
<select class="form-control select2-multi" name="activities" multiple="multiple">
#foreach($activities as $activity)
<option value="{{ $activity->id }}">{{ $activity->activity_name}}
</option>
#endforeach
</select>
{!! Form::close() !!}
// PostsController
public function create()
{
$activities = Activity::all();
return view('posts.create')->withActivities($activities);
$posts = Post::all();
}
public function store(Request $request)
{
// Create a new post using the request data
// Save it to the database
$this->validate(request(), [
'title' => 'required',
'body' => 'required',
]);
$post = Post::create([
'title' =>request('title'),
'body' =>request('body'),
'user_id' => auth()->id(),
'activity_id' => id()
]);
// And then redirect to somewhere in application
return redirect()->route('posts.show', $post->id);
}

Answer 1

This error throw only when you have empty variable but you point in blade file to render / display for browser. Or if you retrieve records from DB then add findOrFail in query to prevent those kind of issues. Thank you.