Offspecular simulation is broken in GUI

On starting any offspec simulation it crashes with assertion

Throwing runtime_error: Assertion false failed in Device/Coord/CoordSystem2D.cpp, line 301

and subsequent segfault.

added GUI crash release-critical labels

assigned to @m.svechnikov

mentioned in merge request !1690 (merged)

mentioned in commit 7d4920a5

closed with merge request !1690 (merged)