Remove Exception typehint to fix T9637

Summary:
Parse errors are caught by the error handler in PHP7, but they may not be of the type Exception
Remove type-hinting so that we can catch them and deal with them

Test Plan: arc unit --everything

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: Korvin, epriestley

Maniphest Tasks: T9637

Differential Revision: https://secure.phabricator.com/D14342