UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.87 Safari/537.36

Steps to reproduce the problem:
1. type the following in console
2. (new Image).srcset = '<!-- this is a placeholder -->';
3. two red errors are thrown

What is the expected behavior?
Other browsers try to load the placeholder regardless, which I think is wrong. However, throwing 2 errors in console is also too much. Shouldn't these just be warnings instead?

What went wrong?
Specially when it comes to templates, having placeholders as attributes is quite common.

In this case Chromium is doing the right thing, ignoring the srcset without trying to load it from the network, but it throws 2 errors even if I instantly update the attribute.

If Chromium could just show a warning instead, that'd be awesome!

Did this work before? N/A 

Does this work in other browsers? Yes

Chrome version: 56.0.2924.87  Channel: n/a
OS Version: OS X 10.11.6
Flash Version: Shockwave Flash 25.0 r0

This is essential to keep mapped literal templates to DOM nodes as simple as possible, without having "scary" errors per srcset.

Thanks for considering some improvement, if possible.