clickable_nicknames is broken in gajim master

clickable_nicknames is broken in gajim master:

10/16/2019 18:45:04 (E) gajim.plugin_system Error while loading a plugin
Traceback (most recent call last):
  File "/Users/rschwab/dev/gajim/gajim/plugins/pluginmanager.py", line 184, in add_plugin
    plugin = plugin_class()
  File "/Users/rschwab/dev/gajim/gajim/plugins/helpers.py", line 107, in wrapper
    result = f(*args, **kwargs)
  File "/Users/rschwab/dev/gajim/gajim/plugins/gajimplugin.py", line 178, in __init__
    self.init()
  File "/Users/rschwab/dev/gajim/gajim/plugins/helpers.py", line 107, in wrapper
    result = f(*args, **kwargs)
  File "/Users/rschwab/.local/share/gajim/plugins/clickable_nicknames/clickable_nicknames.py", line 26, in init
    colors = colors.split(':')
AttributeError: 'NoneType' object has no attribute 'split'

Gajim version: 7b9278ae996ff3d185f5b174f20f27337ecb7c4b