Duplicating CesiumGeoreference causes crash

[j9liu]

In Cesium for Unreal Samples, open the first level. Select the CesiumGeoreference in the World Outliner and hit Ctrl + D. (This will also happen if you copy + paste it. )

First, this breakpoint will trigger in UObjectGlobals.cpp, in StaticFindFirstObject.

Then, this line will have an exception + crash....

The call stack happens in line 149 in Cesium3DTileset.cpp, under ResolveGeoreference():

[kring]

Probably a duplicate of #1189.

[j9liu]

I opened #1680 to fix this, but it does not address #1189. #1189 is also triggered by dereferencing a null georeference, but it happens at tileset creation time.