Update app.py

app.py

@@ -936,7 +936,7 @@ window.snapshot = snapshot;
         forceUpdate
     ) {
         if (!mesh.isVerticesDataPresent(BABYLON.VertexBuffer.PositionKind) || !mesh.isVerticesDataPresent(BABYLON.VertexBuffer.NormalKind) || !mesh.isVerticesDataPresent(BABYLON.VertexBuffer.UVKind)) {
-            alert("Cannot call applyDisplacementMap: Given mesh is not complete. Position, Normal or UV are missing "+!mesh.isVerticesDataPresent(BABYLON.VertexBuffer.NormalKind);
+            alert("Cannot call applyDisplacementMap: Given mesh is not complete. Position, Normal or UV are missing "+!mesh.isVerticesDataPresent(BABYLON.VertexBuffer.NormalKind));
             return mesh;
         }