Fix #115983: Crash when saving empty Composite output Blender crashes when the compositor tries to save en empty composite output through the render pipeline. This happens when no Composite node exist and no Render Layers node is used, essentially producing an empty render result. We fix this by only saving the composite output if a Composite node or a Render Layers node exist. Pull Request: https://projects.blender.org/blender/blender/pulls/117129