Try the other orientation for `n_dates`

Common/util_eddies.py

@@ -105,8 +105,14 @@ class SHPC_class:
 
         # We only need ishape_last for the last slice, for one
         # orientation, in order to define n_dates:
+
         ishape_last = self.get_ishape_last(self.n_slices - 1, def_orient)
 
+        if ishape_last is None:
+            orientation = other_orient(def_orient)
+            ishape_last = self.get_ishape_last(self.n_slices - 1, orientation)
+            assert ishape_last is not None
+
         self.n_dates = np.ediff1d(self.d_init, to_end=ishape_last.size)
         self._i_slice = []