Before the add of Liip_ImageBundle, when you don't have the source image of the variation, that error was logged instead of throws an exception that won't let you view the rest of the page.

This is specially tedious when dev environments when you probably has an updated copy of your prod database but you don't have all the files in prod.

As we did then, i propose to log this error too and so allow to load the rest of the page even in dev env.