Call to Member() on non-object on MemberTableField.php

[sharvey]

Animfx had a problem with the newsletter system, there was a non-object error when you clicked a few times on some draft newsletters, then refreshed the page admin/newsletter.

It was a strange bug, and only occured on the live site.

The fix was to add some extra checks on line 359 of MemberTableField?.php

if($this->group && $this->group->Members()) {

}

This IF block wraps around the whole sourceItems = $this->group->Members() so that it can't reach a non-object (and causing the whole system to fail).

Please ensure this fix is added to the latest branch of SS. If you find there's a better solution, please do that, but this one seems to work fine because there's situations when $this->group doesn't exist on sourceItems()