[Koa] Some koa middleware spans have weird data

[mydea]

We are seeing some spans emitted by the koa instrumentation that look like this:

{
  attributes: {
      'koa.name': '',
      'koa.type': 'middleware',
    },
    name: 'middleware - ',
}

Which I guess comes from here: https://github.com/open-telemetry/opentelemetry-js-contrib/blob/main/plugins/node/opentelemetry-instrumentation-koa/src/utils.ts#L43

I guess there needs to be some more checking there, and/or some fallback behavior if layer.name is empty 🤔

The app that triggers this span is basically:

const Koa = require('koa');
const Router = require('@koa/router');

const app1 = new Koa();

router1.get('/test-transaction', ctx => {
  // do something here...

  ctx.body = {};
});

app1.use(router1.routes()).use(router1.allowedMethods());

app1.listen(port1);

And then visiting /test-transaction.

Note that the router span seems correct:

{
  attributes: {
    'http.route': '/test-transaction',
    'koa.name': '/test-transaction',
    'koa.type': 'router',
  },
  name: 'router - /test-transaction',
}