Fix a crash in get_image_close_to when a tile has no features

[tijszwinkels]

Tiny bugfix; When calling get_image_close_to, the library would crash when the received tile was empty, with a message like this:

  File "/usr/local/lib/python3.9/site-packages/mapillary/utils/auth.py", line 59, in wrapper
    return f(*args, **kwargs)
  File "/usr/local/lib/python3.9/site-packages/mapillary/interface.py", line 110, in get_image_close_to
    return image.get_image_close_to_controller(
  File "/usr/local/lib/python3.9/site-packages/mapillary/controller/image.py", line 134, in get_image_close_to_controller
    and unfiltered_data["features"][0]["properties"] != {}
IndexError: list index out of range

this MR fixes this crash.

[tijszwinkels]

Build failed on building documentation, but no documentation changed.
Failing check is unrelated.

[Rubix982]

Thanks for the PR, @tijszwinkels.

Sure, this is an easy merge.

The documentation workflow fails if no part of the documentation is altered, hence the fail signals that there needs nothing to be done. The documentation is generated from the source code (.py) files. So the fail is okay and can be disregarded.