fix bug in draft path array

put lnodes.normalize() inside try/except block
replace hard-coded 1e-6 with Vector3d::epsilon() in VectorPy::normalize()

src/Base/VectorPyImp.cpp

@@ -451,7 +451,7 @@ PyObject*  VectorPy::normalize(PyObject *args)
     if (!PyArg_ParseTuple(args, ""))
         return 0;
     VectorPy::PointerType ptr = reinterpret_cast<VectorPy::PointerType>(_pcTwinPointer);
-    if (ptr->Length() < 1.0e-6) {
+    if (ptr->Length() < Vector3d::epsilon()) {
         PyErr_SetString(Base::BaseExceptionFreeCADError, "Cannot normalize null vector");
         return 0;
     }