AutoGrouper crashes darktable when darktable is opened in darkroom mode

[wpferguson]

AutoGrouper.lua hides the styles module when it starts. This works fine as long as you are in lighttable mode, but if you are in darkroom mode, there is no styles module to hide, thus when you try it will crash darktable.

[jankirsten]

What is the reason that the styles module needs to hidden in the first place?

[wpferguson]

Fixed by #360