Fixed index page to no longer show the 500 response code.

    posts = posts_master\
        .limit(app.config["POSTS_PER_PAGE"])\
        .offset(page * app.config["POSTS_PER_PAGE"]) .all()

Line was causing the index page to return a 500 response code. Casted the app.config["POSTS_PER_PAGE"] to int to prevent this.