It is worth being precise about what light does, because we tend to hear this as a promise that nothing dark will happen.
Light does not flatten the terrain. It does not remove the road or shorten it. What it does is make the next step visible.
That is a smaller promise than the one we want and a more useful one than the one we imagine. Anyone who has walked at night knows the fear is rarely the distance. It is not knowing where your foot is going.
Whoever follows Me will never walk in darkness. Follows. The light moves. Stand still and you will watch it leave, which is why faith that worked five years ago sometimes feels dim now. The lamp did not fail. It went on ahead.
And He does not say He carries a light. He says He is one. What you are following is not information about the way. It is a person on it.