Error when upgrading koa-compose to 3.0

[ppascher]

Hello,

when I update koa-compose to the recently released version 3.0 I keep getting the following error:

TypeError: downstream.call(...)[(intermediate value)] is not a function
      at Object.<anonymous> (/projects/intranet_redux/backend/node_modules/koa-mount/index.js:58:23)
      at [object Generator].next (native)
      at Object.<anonymous> (/projects/intranet_redux/backend/node_modules/koa-mount/index.js:60:14)
      at [object Generator].next (native)
      at Object.dispatch (/projects/intranet_redux/backend/node_modules/koa-router/lib/router.js:331:14)
      at [object Generator].next (native)
      at Object.<anonymous> (/projects/intranet_redux/backend/node_modules/koa-mount/index.js:58:23)
      at [object Generator].next (native)
      at Object.serve (/projects/intranet_redux/backend/node_modules/koa-static/index.js:41:14)
      at [object Generator].next (native)

I tried looking at the commits from koa-compose since 2.3 but couldn't figure it out.
I currently use it like this

// protected route - check if user has a valid token & permissions for ressource
app.use(mount('/api/v1/', compose([jwt({secret: publicKey, algorithm: 'RS256'}), permissionCheck(), apiRoutes.middleware()])));

[derek-duncan]

I ran into this same error today, but I found a solution you might find useful. First off, the error is occurring because koa-compose 3.0 has been upgraded to koa 2.0. Notably, ctx is now being passed as the first argument in middleware vs being referenced with this. That's why .call is breaking in this case.

I've forked koa-mount and updated the module to work with Koa 2.0. I'm not sure if this should be submitted as a PR, so I'll just link it here. Hope it helps!

koa-mount for Koa 2.0

[ppascher]

Thanks alot!