Unhandled Promise rejection in loadPointCloud

[rooby]

If the XHR request encounters any kind of errors the promise rejects, but the promise rejections aren't handled.
Seems like there are a few places in the code where promise rejections aren't handled.

[fahadm]

Can you provide a minimally reproducible example?

[kamilmingulov]

Loader assumes that Response status is always 200 and attempts to access .json or .buffer both of which can be empty if request failed. I made it fail with 404 requesting nonexistent URL.