I'm always afraid something like this will happen on my long renders. When I close Vue for an internet surfing, I save the image and scene file in their project folder. During the save, I always add an incremental number to the file names. For example, the file names go from 'Project 120-001' to 'Project 120-002' and so on. The '120' is the 120th save while the '001' & '002' are the continued render session versions.

Charles