While trying to figure out how to make a SliderWidget work, I discovered that adding an SCR_SliderComponent without there being a valid SCR_EventHandlerComponent in an expected path, will cause the Workbench to throw this error:

SCRIPT    (E): Virtual Machine Exception

Reason: NULL pointer to instance

Class:      'SCR_SliderComponent'
Function: 'HandlerDeattached'
Stack trace:
Scripts/Game/UI/Components/WidgetLibrary/SCR_Slider/SCR_SliderComponent.c:71 Function HandlerDeattached

Suggested fix: Add an early-exit check to SCR_SliderComponent::HandlerDeattached() if m_Handler is NULL