title: Error contains an invalid type, it should be an object, or a null docker-compose
body: <p>I am getting following error</p>
  <pre><code>version: '3.9'
  
  services:
    app-1:
      container_name: app-1
      image: app/app:1.0.0
      networks:
        app_network:
          - ipv4_address: 192.28.0.2
  
    app-2:
      container_name: app-2
      image: app/app:1.0.0
      networks:
        app_network:
          - ipv4_address: 192.28.0.3
  
    app-3:
      container_name: app-3
      image: app/app:1.0.0
      networks:
        app_network:
          - ipv4_address: 192.28.0.4
  
  networks:
    app_network:
      driver: default
      ipam:
        driver: default
        config:
          - subnet: 192.28.0.0/16
            gateway: 192.28.0.1
  </code></pre>
  <p>Getting following error</p>
  <pre><code>docker-compose up -d
  ERROR: The Compose file './docker-compose.yaml' is invalid because:
  services.app-1.networks.app_network contains an invalid type, it should be an object, or a null
  services.app-2.networks.app_network contains an invalid type, it should be an object, or a null
  services.app-3.networks.app_network contains an invalid type, it should be an object, or a null
  </code></pre>