Capture and report errors when extension media installation fails.
Review Request #8926 - Created May 8, 2017 and submitted
It's possible (and not very hard) to get into situations where extension media installation fails. For instance, if there are permission/ownership issues, we can fail to remove existing extension media and crash when installing new media. This results in HTTP 500 error pages as each access then tries to repeat the media installation, unsuccessfully. We now look for these failure cases, catching the errors and reporting them in a more helpful way. The pages no longer crash (but may not work as expected), and admins can get a hint as to what's wrong in the error logs. There's also a fix for an exception handler's error reporting where the error attempted to use the exception instance, which wasn't defined during the capture.
Tested against a failure case on our server.