Log before unregistering Fixes #9455

[Forgind]

Fixes #9455

Context

If we crash very early—like in the midst of setting up the ProjectLoggingContext—we have all the machinery set up to log information like that the build started, but then we unregister the relevant handlers before we actually log that we'd failed.

Changes Made

Do not unregister handlers until shutdown

Testing

I tested with the repro from #9455, and it now looks like this:

MSBUILD : error MSB4017: The build stopped unexpectedly because of an unexpected logger failure.
MSBUILD : error MSB4017:     Exception of type 'System.Exception' was thrown.
MSBUILD : error MSB4017:        at Microsoft.Build.BackEnd.Logging.ParallelConsoleLogger.ProjectStartedHandler(Object s
ender, ProjectStartedEventArgs e) in C:\GitHub\msbuild\src\Build\Logging\ParallelLogger\ParallelConsoleLogger.cs:line 5
86
MSBUILD : error MSB4017:    at Microsoft.Build.Evaluation.ProjectCollection.ReusableLogger.ProjectStartedHandler(Object
 sender, ProjectStartedEventArgs e) in C:\GitHub\msbuild\src\Build\Definition\ProjectCollection.cs:line 2342
MSBUILD : error MSB4017:    at Microsoft.Build.BackEnd.Logging.EventSourceSink.RaiseProjectStartedEvent(Object sender,
ProjectStartedEventArgs buildEvent) in C:\GitHub\msbuild\src\Build\BackEnd\Components\Logging\EventSourceSink.cs:line 5
33

(with a full stack trace).

Notice that it finds the real exception—just an ordinary System.Exception with no message in this case.

Notes

I went directly against the advice of a comment to make this change. I tried to see what motivated that comment, but it came with the initial commit along with all the code next to it. Regardless, it does not make me feel good to do so. I don't understand why the comment should be true, but please do read it and let me know if this is a horrible idea.

I also intentionally reused MSB4017 because this feels like the same exception, and I didn't want to confuse people. I just added some extra formatting around it. Like with going against the comment, I can find a new number if reviewers don't like that idea.

[JanKrivanek]

Unexpected order of messages seems less harm then losing the exception info - so the change looks good to me.

I'm just wondering whether the rethrowing info wouldn't be helpful as well