Bugfix: FileSystemWatcher - crash when there is an error

[bryphe]

Issue: On Windows, I noticed that when I built the unit tests, Oni would crash and just show a blank screen.

Defect: chokidar was emitting several error events around the fileysystem, for exampe:

events.js:182 Uncaught Error: EPERM: operation not permitted, lstat 'E:\oni\lib_test\browser\src\Input'

This was easy to repro on Windows by running npm run test:unit:browser while the E:/oni directory was the active workspace, or by deleting the lib_test folder.

Fix: Handle the 'error' event and log out warnings. These aren't usually actionable for us, and are just noise - for example, it's expected when the lib_test folder is deleted that you'd get an error trying to access a subdirectory, and we don't need to do anything special. However, handling the error event means it doesn't bubble up and crash the editor.

[codecov]

Codecov Report

Merging #2142 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #2142   +/-   ##
=======================================
  Coverage   36.83%   36.83%           
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  Files         293      293           
  Lines       11982    11982           
  Branches     1582     1582           
=======================================
  Hits         4414     4414           
  Misses       7320     7320           
  Partials      248      248

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