ENH: Raise IndexError on empty slices

Author: effigies

nibabel/spatialimages.py

@@ -339,7 +339,11 @@ def __getitem__(self, slicer):
             slicer = self.check_slicing(slicer)
         except ValueError as err:
             raise IndexError(*err.args)
+
         dataobj = self.img.dataobj[slicer]
+        if np.any(dataobj.shape == 0):
+            raise IndexError("Empty slice requested")
+
         affine = self.slice_affine(slicer)
         return self.img.__class__(dataobj.copy(), affine, self.img.header)