ComposedCubeMapTexture example not working

[ricklentz]

Describe the bug
snap install on Ubuntu 18.04.5 LTS (Bionic Beaver)

To Reproduce
Steps to reproduce the behavior:

1. Go to examples
2. Click on the dolphin 'ComposedCubeMapTexture.x3d' example from the grid display of samples.
3. See error: "Unrecognized image file format
   ########## /home/holger/Projekte/Titania/snap/parts/titania/build/libtitania-x3d/Titania/X3D/Browser/X3DBrowserContext.cpp:400: in function 'update': "

Expected behavior
See the X3D animation with textured geometry. The exceptions prevent the texture from loading but the geometry and animation works (the background textures also work). See below for an illustration.

Screenshots