I had the glitch where you cannot communicate with Sapphire about the Shadr quest. I evidently did not reply properly when I first entered Riften. I tried the Amulet of Mara trick but she just ignored me. Finally, I just got tired of being blown off by Sapphire and I tried to get her to react by punching her. She did not take to that and came after me with a knife. The Riften guards did not appreciate that and took her out. So, now what? Is Sapphire essential to any other quest? I know she is part of the Thieves Guild but how essential is she?

She's not involved in any other quest I'm aware of.

She's not essential in anything but that one quest

Thanks