Why do I have white spaces in my lantern when I combine my objects to my frame?

This will happen mostly in Inkscape when Path>Combine is used instead of Path>Union. Union will merge one or more objects together. Below is an example of what happens when Path>Combine is used:

To fix this, simply undo the action by using CTRL+Z (Windows) or Cmd+Z (Mac) on your keyboard or go to Edit>Undo.  Select your objects again and choose Path>Unite. This can also be fixed by selecting each white area with your nodes tool and pressing delete on your keyboard to remove those nodes.