Localeditor demo breaks completely if files cannot be loaded

[kossebau]

http://www.webodf.org/demo/ci/wodotexteditor-0.5.7/localeditor.html

1. Load a document which webodf does not support (e.g. append #nofile to the url)
2. Click "load" button to load another document

Expected:
another document can be loaded

Actual:
throws an assertion