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Fix unit test

* This way we can easier load files conditionally

Http range requests support is required for video preview

When download a public link share folder using the button on the top
right, it doesn't provide a list of files.

This fix makes sure to trigger the correct logic when no file list was
given.

Probably nice for the people that contributed to 9.0 to see themselves in the AUTHORS file :)

* Made comments more clear
* Removed unneeded methods
* IShares shareTime is now a proper DateTime object
* IShares getPath -> getNode & setPath -> setNode
* Fix unit tests

* Updated unit tests

Nice side effect... pure unit tests!

This commit consists of patches automatically generated for this project on https://scrutinizer-ci.com

Currently the `getPath` methods returned `NULL` in case when a file with the specified ID does not exist. This however mandates that developers are checking for the `NULL` case and if they do not the door for bugs with all kind of impact is widely opened.

This is especially harmful if used in context with Views where the final result is limited based on the result of `getPath`, if `getPath` returns `NULL` PHP type juggles this to an empty string resulting in all possible kind of bugs.

While one could argue that this is a misusage of the API the fact is that it is very often misused and an exception will trigger an immediate stop of execution as well as log this behaviour and show a pretty error page.

I also adjusted some usages where I believe that we need to catch these errors, in most cases this is though simply an error that should hard-fail.