Crash when encountering class attributes that are aliases

[IljaManakov]

Hi,

I have encountered an issue where autodocsumm crashes when it encounters a class attribute that is a type instance (i.e. it is just an alias). What appears to happen is the following:

• autodoc's ClassCodumenter's get_doc returns None for aliases.
• AutoSummary's get_grouped_documenters attempts to iterate over the return value of get_doc
• Combined, this results in a TypeError when a class has a type instance as an attribute

minimal-example.zip

[EpicWink]

Fixed by #42

[Chilipp]

Thanks for reporting @IljaManakov! This issue has been closed via #42.