[BUG] NPE related to MainFileListViewModel

[Aitorbp]

Related Issues

App:https://github.com/owncloud/android/issues/4065

• [x] Added changelog files for the fixed issues in folder changelog/unreleased. More info here

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QA

[jesmrec]

Nothing to test here, just waiting for next release. If the crash does not happen anymore, please close the issue then