The assertion is observed with metal pipeline, with monkey test (ChoiceBox's popup menu). The app crashes, when Metal API Validation is enabled, due to an incorrect scissor rect.
Crash does not occur when Metal API Validation is NOT enabled,

-[MTLDebugRenderCommandEncoder setScissorRect:]:4048: failed assertion `Set Scissor Rect Validation
(rect.x(0) + rect.width(248))(248) must be <= render pass width(238)
'
zsh: abort java @build/run.args -jar dist/MonkeyTester.jar

Steps:
1. Make sure Metal API Validation is enabled
2. Launch Monkey Tester app
3. Choose ChoiceBox on left pane in the app
4. Click on ChoiceBox in main pane
5. The Popup menu would be shown
6. Make sure the mouse is over the pupup menu
7. Scroll Up using two fingers scroll on touch pad
=> App crashes with above assertion

Keeping the priority to P4, as the issue happens only when Metal shader validation is enabled.