Error when using tilde in author field

[goodole]

When using tilde in author: field in content I get this error:

Traceback (most recent call last):
File "/usr/local/bin/wok", line 4, in
Engine()
File "/usr/local/lib/python2.7/site-packages/wok/engine.py", line 100, in init
self.generate_site()
File "/usr/local/lib/python2.7/site-packages/wok/engine.py", line 137, in generate_site
self.load_pages()
File "/usr/local/lib/python2.7/site-packages/wok/engine.py", line 299, in load_pages
p = Page.from_file(os.path.join(root, f), self.options, self, renderer)
File "/usr/local/lib/python2.7/site-packages/wok/page.py", line 116, in from_file
page.build_meta()
File "/usr/local/lib/python2.7/site-packages/wok/page.py", line 208, in build_meta
.format(self.meta['slug']), authors.type)
IndexError: tuple index out of range