Conpherence - fix fatal on list view for 100+ messages

Summary: Fixes T6480. @epriestley is very popular and has over 100 messages, thus triggering this issue. fix the typo because bugs are bad.

Test Plan: set limit to 1, observed fatal, applied patch and fatal went away

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin, epriestley

Maniphest Tasks: T6480

Differential Revision: https://secure.phabricator.com/D10793