"compileDebug" is default on (if you are not minifying).
This is causing some code to get injected which appears to be relying on the EJS runtime.
The offending code is part of a "rethrow" function which throws an exception on:
var filename = utils.escapeXML(flnm);
Unsure what the fix is here. Perhaps the "ejs" library should be including the utils module when "client" is true.
It might be more appropriate to make "compileDebug" default false, or at least document any side-effects. This took me by surprise.