Does not work with node v6.5

[koajs]

Does not work with node v6.5

[targos]

This is a bug in V8 with tail call optimization. The --harmony-tailcalls flag (implied by --harmony) is enough to trigger it. It will probably not be fixed in Node.js because the feature is not considered stable in V8 5.1.
I suggest you drop the --harmony flag and if you really need one of the features that it activates, enable it directly. Here is the list: https://github.com/nodejs/node/blob/v6.5.0/deps/v8/src/flag-definitions.h#L211-L216

[bishtawi]

Did some more testing. Its due to the --harmony flag that I am including when running node.

Smallest failing test case:

const Koa = require('koa')
const convert = require('koa-convert')
const session = require('koa-generic-session')

const app = new Koa()
app.use(convert(session()))

app.listen(3000)

Running node --harmony index.js then hitting localhost:3000 in a webbrowser returns a 500 instead of the expected 404.

Running without the harmony flag works as expected.

[bishtawi]

Adding @targos

[gyson]

Which version do you use ? (for koa, koa-convert & koa-generic-session)

[bishtawi]

Ah, good question. I should have mentioned it in my original post.

Koa: 2.0.0
Koa-convert: 1.2.0
Koa-generic-session: 1.11.3

[gyson]

Thanks for the detailed report. The stacktrace looks a little bit strange. It basically says that calling generator.next() will return undefined instead of { done, result } protocol. I think it's more likely to be a nodejs/V8 bug.

Also, --harmony flag is usually not suitable for production.

[bishtawi]

Thanks everyone. I removed the harmony flag and my app works fine. Looks like the only reason why I had it was due to needing it back in the old node 0.12.x to get generators, arrow functions, promises, block scoping, etc.

[bishtawi]

Closing as its a bug in V8