Problem deploying on apache - Exception in onResRdy: TypeError: Cannot read property 'htmlRes' of undefined

I’m starting out with meteor but have hit a problem. I get the following error message in the Chrome console:

Exception in onResRdy: TypeError: Cannot read property ‘htmlRes’ of undefined

I am running the standard todos app, using Meteor 1.3 and an Apache2 webserver on ubuntu trusty.

The app runs fine on domain.com:3000 - the error message only appears when I run it (with proxy) on domain.com/todos. The page itself does not display.

My proxy settings:

ServerAdmin mark@mydomain.com
ServerName monkl
ServerAlias www.mydomain.dom

    <Directory />
      Options FollowSymLinks
      AllowOverride None
      Require all granted
    </Directory>

    ProxyRequests Off
    <Proxy *>
      Order deny,allow
      Allow from all
    </Proxy>

    <Location /todos>
      ProxyPass http://127.0.0.1:3000
      ProxyPassReverse http://127.0.0.1:3000
   </Location>

Thanks for your help! Mark