Fix assert in eig2x2_fx optimisation
Summary
The eig2x2_fx optimisation is making an assert fail somewhere in the renderer.
Edited by Vladimir Malenovsky
WARNING! Gitlab maintenance operation scheduled for Monday, 20 April between 12:00 and 14:00 (CET). During this time window, short service interruptions (less than 5 minutes) may occur. Thank you in advance for your understanding.