Cannot read property 'src' of undefined

[chrislim]

I noticed that the bug I was encountering in this issue assemble/assemble#547 may have been caused by this line/the following line:
https://github.com/helpers/handlebars-helper-compose/blob/master/index.js#L52
ctx.page is undefined so an error is thrown when we try to reference src from it.

I added a try catch block around it and suppressed the error and it seems like the build succeeds and the site runs. However, I didn't get a chance to examine the wider to context to see why ctx.page is undefined when passed in the first place and also why the error doesn't show up until I have more than 10 pages to render (.hbs files). The catch block seemed to be hit even when I had less than 10 pages, but grunt would not throw the error

Warning: Cannot read property 'src' of undefined

Unless I had more than 10.