nginx config for epress app running on port 3000

I'm trying to setup nginx so that it pull the app running on port 3000.

When I visit mydomain.com:3000, the app works. I want it to run without the port.

I have nginx setup and it's working properly. I have an SSL cert setup and it's working properly (I'm able to see the nginx start page with SSL) I have the www redirect working properly.

The part I want to do now is take what is running on port 3000 and have it run on port 80.

Here is my config file:

upstream myapp {
  server 127.0.0.1:3000;
}

server {
    #listen 80 is default
    server_name www.mydomain.com;
    return 301 $scheme://mydomain.com$request_uri;
}

server {
    listen 80;
    listen   [::]:80;
    listen   443 default ssl;
    ssl on;
    ssl_certificate    /root/certs/bundle.crt;
    ssl_certificate_key    /root/certs/mydomain.key;   

    server_name mydomain.com;

    if ($ssl_protocol = "") {
       rewrite ^   https://$server_name$request_uri? permanent;
    }

    location / {
      proxy_set_header  X-Real-IP  $remote_addr;
      proxy_set_header  X-Forwarded-For $proxy_add_x_forwarded_for;
      proxy_set_header  Host $http_host;
      proxy_redirect  off;
      try_files @node $uri.html;
    }

    location @node {
      proxy_pass https://myapp;
    }

}

When I visit the page with this setup, I get a 500 internal server error. What am I doing wrong?