To reproduce:
1. Open project, found in owncloud https://oc.unity3d.com/index.php/s/0CQo6c7fvCZsb3Z
2. In Hierarchy window, select image target and create a cube for a child
3. In Inspector window, add Virtual Button component
4. Remove Mesh Renderer component (can be done several times)

Expected: mesh renderer component is removed
Actual: 3d shape used gets corrupted until project is restarted (check VufRenderer.gif)

Reproduced in: 2017.2.0p4, 2017.3.0f1, 2018.1.0a6

Note: legacy Vuforia not tested due to being obsolete
Note2: geometry corruption results differ depending on how many times Mesh Renderer is removed (check picture VufRend1.png)
Note3: errors appear:

"Mesh.vertices is too small. The supplied vertex array has less vertices than are referenced by the triangles array.
UnityEngine.Mesh:set_vertices(Vector3[])"

"Mesh.uv is out of bounds. The supplied array needs to be the same size as the Mesh.vertices array.
UnityEngine.Mesh:set_uv(Vector2[])"