Fix 404 handling for endpoints matching short URLs

src/invidious.cr

@@ -5058,6 +5058,11 @@ error 404 do |env|
       response = client.get(response.headers["Location"])
     end
 
+    if response.body.empty?
+      env.response.headers["Location"] = "/"
+      halt env, status_code: 302
+    end
+
     html = XML.parse_html(response.body)
     ucid = html.xpath_node(%q(//meta[@itemprop="channelId"]))