Laravel Page is not being displayed, until I refresh the window

I am working on a laravel project, I encountered with an error i.e, page content is not being displayed until I refresh the page. If I do refresh my page, desired page will opens up. Here is my code, inside which I mentioned which part is throwing error:

  public function adduser(Request $request){
    //take a project of logged in user and a user to it
    $project = Project :: find($request->input('project_id')); 
    if(Auth::user()->id==$project->user_id){
        if($user = User::where('email', $request->input('email'))->first()){//first for single record
            //Check if user is already added to project
            $projectUser = ProjectUser::where('user_id',$user->id)
                                        ->where('project_id',$project->id)
                                        ->first();
            if($projectUser){
                //if user already exist; exit.
                return redirect()->route('projects.show',['$project'=> $project->id])
                ->with('success',$request->input('email'). 'is already a member of this project.');
            }
            if($user && $project){
                $project->users()->attach($user->id);
                return redirect()->route('projects.show',['$project'=> $project->id])
                ->with('success',$request->input('email'). 'has been added successfully.');
            }
        }
        else{//user is not registered, so do not add him
            //This link is not working until I refresh the page???
            return redirect()->route('projects.show',['$project'=> $project->id])
            ->with('errors', 'This User doesnt exist');
        }
    }else{
        return redirect()->route('projects.show',['$project'=> $project->id])
        ->with('errors', 'You are not authorized to do this.');
    }

}

via Chebli Mohamed