Evaluate returns undefined but chromium correctly has value inside evaluate

Steps to reproduce

Tell us about your environment:

• Puppeteer version: 1.3.0
• Platform / OS version: OS X Sierra 10.12.6
• URLs (if applicable):
• Node.js version: 8.10.0

What steps will reproduce the problem?

You can run this gist here: https://gist.github.com/chrisabrams/a2a098d1b2d697f349f4e1ad1be98602

What is the expected result? The expected result is that evaluate will return the list of nodes

What happens instead? Instead, evaluate returns undefined

[vsemozhetbyt]

If I get this right, DevTools protocol cannot serialize an array of nodes and resolves it to undefined. If you make it an array of strings, this works:

return nodes.map(({ innerText }) => innerText)

[yanivefraim]

How about throwing an error when evaluate returns a non-Serializable value? cc @aslushnikov