Uncaught SyntaxError: Unexpected token

I’m developing sites locally, so I can show code.

Across a couple of local sites, I get this error in console:
‘Uncaught SyntaxError: Unexpected token <‘.
Console points to the first line of the html document produced by wordpress: the html doctype.

The common element seemed to be the deferred scripts plugin.

If I disable the plugin, the error goes away.

Other then this, the plugin functions as expected: scripts still load from the footer using LAB, and run as expected.

http://wordpress.org/plugins/wp-deferred-javascripts/