Fix bug that caused repositories to not be found

[westbury]

fixes #7860

What it does

When upgrading to Typescript 3.9.1-rc, a line of code was detected as being in error and corrected appropriately. A test on stat.isDirectory was corrected to stat.isDirectory(). However this actually introduced a problem because the code was no longer being called for files. Most of the code should not have been called for files, though it was harmless to do so because findGitRepositories returned an empty array and the rest of the code operated on empty arrays. However the final resolve to [] was needed. Failure to resolve the promise when a file ultimately broke the repository locator.

A simple fix would have been to resolve when a file. However it is not necessary to wrap this in a Promise so I removed that. If there is some reason the Promise wrapper is wanted then we can leave that, but be sure to resolve it also in the inner error handler.

How to test

Check that all expected Git repositories are found. Check various situations (changing workspaces, adding and removing repositories, nested repositories, error conditions etc).

Review checklist

• as an author, I have thoroughly tested my changes and carefully followed the review guidelines

Reminder for reviewers

• as a reviewer, I agree to behave in accordance with the review guidelines

[502647092]

@westbury Looks like it's fixed

[akosyakov]

thank you for fixing it!