diff --git a/components/Timetable.vue b/components/Timetable.vue
index e3795d8..5143339 100644
--- a/components/Timetable.vue
+++ b/components/Timetable.vue
@@ -180,7 +180,7 @@ function* spansFromJunctions(
 		for (const edge of start.edges) {
 			if (edge.type === "start") {
 				for (const location of edge.slot.locations) {
-					activeLocations.get(location)!.add(edge.slot)
+					activeLocations.get(location)?.add(edge.slot)
 				}
 			}
 		}
@@ -196,7 +196,7 @@ function* spansFromJunctions(
 		for (const edge of end.edges) {
 			if (edge.type === "end") {
 				for (const location of edge.slot.locations) {
-					activeLocations.get(location)!.delete(edge.slot)
+					activeLocations.get(location)?.delete(edge.slot)
 				}
 			}
 		}