fix typo

Author: erossignon

lib/shapeFactory.js

@@ -54,7 +54,7 @@ exports.makeBottle = function (occ, parameters) {
 
     const aWire = occ.makeWire(aHalfWire, aMirroredWire);
 
-    asser(aWire.isClosed);
+    assert(aWire.isClosed);
 
     const aFace = occ.makeFace(aWire);
     assert( 1 === aFace.numWires);