Argument 2 passed to App\Providers\AuthServiceProvider::App\Providers\{closure}() must be an instance of App\Post, string given, - laravel-5.7

Question

Am getting the above error when i try to edit a blog post on my laravel 5.7 App. Any ideas on how to resolve this?
My Post Controller;
public function edit($id)
{
$post = Post::find($id);
return view('posts.edit')->withPost($post);
}
/**
* Update the specified resource in storage.
*
* #param \Illuminate\Http\Request $request
* #param int $id
* #return \Illuminate\Http\Response
*/
public function update(Request $request, $id)
{
// Form validation
$this->validate($request, array(
'title' =>'required|max:190',
'category' =>'required|max:190',
'body' =>'required'
));
//save in db
$post = Post::find($id);
$post->title=$request->input('title');
$post->category=$request->input('category');
$post->body=Purifier::clean($request->input('body'));
$post->save();
Session::flash('success','Blog successfuly updated!');
return redirect()->route('posts.show',$post->id);
}
My AuthServiceProvider;
public function registerPostPolicies()
{
Gate::define('create-post', function($user){
$user->hasAccess(['create-post']);
});
Gate::define('update-post', function($user, Post $post){
$user->hasAccess(['update-post']) or $user ->id ==$post -> user_id;
});
Gate::define('delete-post', function($user, Post $post){
$user->hasAccess(['delete-post']) or $user ->id ==$post -> user_id;
});
}
I have spent several hours trying to resolve the issue, but i dont seem to be making any progress.
Any help will be highly appreciated