Merge pull request #45 from DoodleIncident/orfix

bugfix #40: don't try to color non-matching groups

colout/colout.py

@@ -484,6 +484,8 @@ def colorup(text, pattern, color="red", style="normal", on_groups=False):
             # but that match.start(0) refers to the whole match, the groups being indexed in [1,n].
             # Thus, we need to range in [1,n+1[.
             for group in range(1, nb_groups+1):
+                # If a group didn't match, there's nothing to color
+                if match.group(group) is not None:
                     partial, end = colorout(text, match, end, group_colors[group-1], group_styles[group-1], group)
                     colored_text += partial