The line art modifier added a wmNotifier in it's GpencilModifierTypeInfo.generateStrokes callback which isn't thread-safe when called from the depsgraph. This was from the original inclusion of the feature [0] however a more recent optimization to notifier lookups [1] made the crash occur more frequently. Remove the notifier as modifiers should not be adding WM level events and it works without it. [0]:3e87d8a431[1]:0aaff9a07d