Notice error in bp_get_group_join_button() for non members of private groups

[imath]

Actually, the problem doesn't exist in 1.8.1. This is something i've only noticed in 1.9-beta1

If a group is private, then if the logged in user is not a member of this group, in the groups directory, bp_get_group_join_button() causes a notice error as $group->is_invited is not defined.

I suggest the diff attached (simply adds an isset check)

[boonebgorges]

Good catch.

The suggestion in 5269.diff is a workaround for the fact that the properties aren't set correctly in the first place. I think I'd rather fix the root issue.

[boonebgorges]

In 7616:

Refactor get_group_extras logic in group loops

The previous logic made it so that is_pending, is_invited, and is_member
values were only set in the case where users had a membership for the group
in the database. This could result in PHP warnings in certain cases, and in
all cases results in inconsistent data structures between member and non-member
groups within group loops.

Fixes #5269