Enhance debug log output for stacktraces
Make MediaWiki\Logger\LegacyLogger and
MediaWiki\Logger\Monolog\LineFormatter better at outputting stacktrace
information and provide support for 'exception' data in the logging
context that is a structured array in addition to the default Exception
object support. This works with MWExceptionHandler::handleFatalError
generated data that is provided by an HHVM interpreter and cannot be
delivered as an Exception class.
With this patch, a good value for LineFormatter's format would be:
"%datetime% %extra.host% %extra.wiki% %channel% %level_name%: %message%
%context% %exception%\n"
Bug: T89169
Bug: T107440
Change-Id: Ida01ed51c573e1654346e716723e543a1be63090