why the if condition doesn't check the nulls

Question

I was trying to check the null in my var but it throws "Object reference not set to an instance of an object."

 private void GenerateImage()
    {
        //Webster.Client.Modules.Metadata.Helper test = new Webster.Client.Modules.Metadata.Helper();
         var selectedstory = Webster.Client.Modules.Metadata.Helper.SelectedStoryItem;

        if((selectedstory.Slug).Trim()!=null)
        {
         //if (!string.IsNullOrEmpty(selectedstory.Slug))
       //{

           if (File.Exists(pathToImage))
           {
              }
           else
           {
               this.dialog.ShowError("Image file does not exist at the specified location", null);
           }
       }
       else
       {
           this.dialog.ShowError("Slug is Empty,please enter the Slug name", null);
       }
    }

I know selectedstory.Slug has the null value, which is why I used an if condition to check, but it's throwing right there in the if condition.

Can some one please advise what is the right way to check.

Answer 1

You can't call methods on a null reference. Take out the .Trim().