A fix for T83187 (rBf83aa830) assumed in the overlay code of the uv editor that the object was a mesh when it did not have to be - causing a crash. The fix makes sure that the object is a mesh. Reviewed By: jbakker, campbellbarton Maniphest Tasks: T85499, T85495 Differential Revision: https://developer.blender.org/D10369