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;
     }

src/Mod/Draft/Draft.py

@@ -6037,9 +6037,10 @@ class _PathArray(_DraftObject):
             b = nullv
             FreeCAD.Console.PrintLog ("Draft PathArray.orientShape - Cannot calculate Path normal.\n")
         lnodes = z.cross(b)
-        if lnodes != nullv:
+        try:
             lnodes.normalize()                                       # Can't normalize null vector.
-                                                                     # pathological cases:
+        except:
+            pass                                                     # pathological cases:
         if n == nullv:                                               # 1) can't determine normal, don't align.
             psi = 0.0
             theta = 0.0