System Information
Operating system: Windows 10 Pro
Graphics card: GTX 1660 super
Blender Version
Broken: (example: 2.80, edbf15d3c044, master, 2018-11-28, as found on the splash screen) 3.1 alpha
Worked: (newest version of Blender that worked as expected) Haven't tested I only used 3.1
Short description of error separation in edit mode crashes the app
Exact steps for others to reproduce the error
Based on the default startup or an attached .blend file (as simple as possible).
add mesh ->cube ->select it -> tab ->scale on Y axis -> extrude upward faces -> merge edges by scaling on Y/X axis to 0 and enable auto merge vertices ->select the new faces -> separate -> crashed