diff --git a/src/containers/building_blocks.jl b/src/containers/building_blocks.jl
index 0ce1465699f28562c3e5e78c53d35faabbd4e9d2..62f4ae8733ca5e6d5abf364e2d2f5323831212dc 100644
--- a/src/containers/building_blocks.jl
+++ b/src/containers/building_blocks.jl
@@ -79,6 +79,7 @@ function gradient_orientation(bb::BaseBuildingBlock)
             return gradient_orientation(e)
         end
     end
+    error("No gradient orientation found for building block $bb")
 end