Summary:
Depends on D20137. Ref T13250. Ref T12101. In versions of PHP beyond 7, various engine errors are gradually changing from internal fatals or internal errors to `Throwables`, a superclass of `Exception`.
This is generally a good change, but code written against PHP 5.x before `Throwable` was introduced may not catch these errors, even when the code is intended to be a top-level exception handler.
(The double-catch pattern here and elsewhere is because `Throwable` does not exist in older PHP, so `catch (Throwable $ex)` catches nothing. The `Exception $ex` clause catches everything in old PHP, the `Throwable $ex` clause catches everything in newer PHP.)
Generalize some `Exception` into `Throwable`.
Test Plan:
- Added a bogus function call to the rendering stack.
- Before change: got a blank page.
- After change: nice exception page.
{F6205012}
Reviewers: amckinley
Reviewed By: amckinley
Maniphest Tasks: T13250, T12101
Differential Revision: https://secure.phabricator.com/D20138
b9a1260ef5