Replace all "attach first..." exceptions with assertAttached()
Summary:
Ref T3599
Go through everything, grep a bit, replace some bits.
Test Plan: Navigate around a bit
Reviewers: epriestley
Reviewed By: epriestley
CC: Korvin, aran
Maniphest Tasks: T3599
Differential Revision: https://secure.phabricator.com/D6871