fix_web_spotify.user.js

// ==UserScript==
// @name        Spotify app only
// @namespace   com.fiaxhs
// @description Launch app, kill that web player (with fire)
// @include     https://play.spotify.com*
// @include     https://open.spotify.com*
// @version     1
// @grant       none
// ==/UserScript==

// Firefox users: (you'll need GreaseMonkey)
// 1. open about:config
// 2. search "dom.allow_scripts_to_close_windows"
// 3. set it to true.

// Chrome users: 
// 1. save this as a file (ending in `user.js`)
// 2. open chrome://extensions/ and drop said file

// If nothing happens, try to open a spotify URI ( like spotify:track:4uLU6hMCjMI75M1A2tKUQC ) 
// in your browser, and choose to open Spotify app

if (matches = /(album|track|user\/[^\/]*\/playlist)\/([^\?]*)/.exec(window.location)) {
    window.location = 'spotify:' + matches[1] + ':' + matches[2];
    window.setTimeout(() => window.close(), 500);
}