Owl: Picture walking toward a glass door that slides open only when you get close — but for this thought experiment, you never quite step through. Still, people watching can say where you're heading.
A limit is that "heading" language for functions. It describes how outputs behave as inputs approach a value, not necessarily what the function returns if you plug the value in.
On the board: a delivery-drone altitude that follows a nice formula everywhere except at the warehouse gate x = 3, where the log skips a reading. Left and right tables still settle toward the same height.
So — if the function is undefined at a point, does that automatically kill the limit?