Modify stride assertion in `numpy-map.hpp` to be valid for empty vector (#321)

* Set stride assert to be less than INT_MAX

* Remove extra print calls and flush on print

* Revert "Remove extra print calls and flush on print"

This reverts commit cc7db3d0.

* core: fix assert

Co-authored-by: Justin Carpentier <justin.carpentier@inria.fr>

include/eigenpy/numpy-map.hpp

@@ -157,8 +157,7 @@ struct NumpyMapTraits<MatType, InputScalar, AlignmentValue, Stride, true> {
     else
       rowMajor = (PyArray_DIMS(pyArray)[0] > PyArray_DIMS(pyArray)[1]) ? 0 : 1;
 
-    assert((PyArray_DIMS(pyArray)[rowMajor] < INT_MAX) &&
-           (PyArray_STRIDE(pyArray, rowMajor)));
+    assert(PyArray_DIMS(pyArray)[rowMajor] < INT_MAX);
     const int R = (int)PyArray_DIMS(pyArray)[rowMajor];
     const long int itemsize = PyArray_ITEMSIZE(pyArray);
     const int stride = (int)PyArray_STRIDE(pyArray, rowMajor) / (int)itemsize;