Catch/ignore/handle exceptions from FileSystemGlobbing

[jakebailey]

There seem to be quite a few of exceptions coming out of FileSystemGlobbing, which is only used inside of LoadDirectoryFiles. Most frequent is an UnauthorizedAccessException:

 at System.IO.Enumeration.FileSystemEnumerator`1.CreateDirectoryHandle(String path, Boolean ignoreNotFound)
 at System.IO.Enumeration.FileSystemEnumerator`1..ctor(String directory, EnumerationOptions options)
 at System.IO.Enumeration.FileSystemEnumerable`1..ctor(String directory, FindTransform transform, EnumerationOptions options)
 at System.IO.Enumeration.FileSystemEnumerableFactory.FileSystemInfos(String directory, String expression, EnumerationOptions options)
 at System.IO.DirectoryInfo.InternalEnumerateInfos(String path, String searchPattern, SearchTarget searchTarget, EnumerationOptions options)
 at Microsoft.Extensions.FileSystemGlobbing.Abstractions.DirectoryInfoWrapper.EnumerateFileSystemInfos()+MoveNext()
 at System.Collections.Generic.List`1.AddEnumerable(IEnumerable`1 enumerable)
 at System.Collections.Generic.List`1.InsertRange(Int32 index, IEnumerable`1 collection)
 at Microsoft.Extensions.FileSystemGlobbing.Internal.MatcherContext.Match(DirectoryInfoBase directory, S

But we also see DirectoryNotFoundException, IOException, PathTooLongException, and FileNotFoundException.

Right now, these exceptions during workspace/didChangeConfiguration go unhandled, produce an error message for the user via RPC, and record the exception.

Looking at the call site:

if (!_filesLoaded) {
    await LoadDirectoryFiles();
}
_filesLoaded = true;

It may be better idea to do something on the order of:

if (!_filesLoaded) {
    try {
        await LoadDirectoryFiles();
        _filesLoaded = true;
    } catch (Exception ex) when (!ex.IsCriticalException()) {
        // Log something to the user
    }
}

That way, we don't record events that are really just errors in the user's configuration and also give feedback as to what's wrong.

[MikhailArkhipov]

DirectoryNotFoundException is IOException as is FileNotFoundException. Basically IO produces IOException, UnauthorizedAccessException and ArgumentException.

[jakebailey]

Fixed in #498.