scenes/scene: Fix crash when context["engine"]["msec"] is invalid (None)
scenes/scene: Fix crash when context["engine"]["msec"] is invalid (None)

Signed-off-by: Takeshi HASEGAWA <80595b5c49522665976d35e515d02ac963124d00@gmail.com>

deathmetalland/IkaLog,deathmetalland/IkaLog,deathmetalland/IkaLog,hasegaw/IkaLog,hasegaw/IkaLog,hasegaw/IkaLog