R1:e03079aaaad2

Try harder to present display/rendering exceptions to the user using standard exception handling

Summary:
Ref T13250. When exceptions occur in display/rendering/writing, they currently go straight to the fallback handler. This is a minimal handler which doesn't show a stack trace or include any debugging details.

In some cases, we have to do this: some of these exceptions prevent us from building a normal page. For example, if the menu bar has a hard fatal in it, we aren't going to be able to build a…