bug: Message details (payload) not rendered correctly when $ref is used in channels

[ashmit-coder]

Description

As reported in the VS code AsyncAPI preview Extension. asyncapi/vs-asyncapi-preview#204

The config used is the default VS-extension config.

<script>
        AsyncApiStandalone.render({
          schema: {
            url: '${asyncapiWebviewUri}',
            options: { method: "GET", mode: "cors" },
          },
          config: {
            show: {
              sidebar: true,
              errors: true,
            },
            parserOptions: { path: '${asyncapiBasePath}' }
          },
        }, document.getElementById('asyncapi'));
</script>

This is an upstream bug report as dicussed in the refrenced issue