Application crashes when "Shadow Mapping" is chosen

Tested with MacOS. Does not reproduce with Linux.

Test steps to reproduce:
1. Add a new basic object, choose the object's material and create a new material from Inspector palette
2. Import a material asset e.g. walnut_matte
3. Set material's Shader to walnut_matte
4. Check the checkbox "Shadow Mapping"
-> Application crashes. Crash report attached.