handle an empty data set

cliff/formatters/table.py

@@ -32,7 +32,11 @@ class TableLister(ListFormatter):
         # first row and set the alignment of the
         # output accordingly.
         data_iter = iter(data)
+        try:
             first_row = next(data_iter)
+        except StopIteration:
+            pass
+        else:
             for value, name in zip(first_row, column_names):
                 alignment = self.ALIGNMENTS.get(type(value), 'l')
                 x.set_field_align(name, alignment)