Error when annotating arguments with Optional[Dict]

[jni]

Describe the bug

I don't have a minimum reproducible example yet. I don't think it'll be hard to produce but wanted to get something written down. When annotating an argument with "Optional[Dict] = None", I get an error from issubclass in this line:

https://github.com/napari/magicgui/blob/481f665af1992c0c99eabe4d608e1d0b6da78e54/magicgui/type_map.py#L85-L86

It tries to evaluate issubclass(typing.Dict, type(None)), which fails with:

TypeError: issubclass() arg 1 must be a class

Changing the annotation to Optional[dict] (no typing) bypasses the error.

Environment:

• OS: Mac
• backend: PyQt5
• magicgui version 0.2.10/master

[tlambert03]

ok thanks!