D20605: Fix null-dereference on malformed tar files

[Aleix Pol Gonzalez]

apol accepted this revision.
This revision is now accepted and ready to land.

REPOSITORY
  R243 KArchive

BRANCH
  master

REVISION DETAIL
  https://phabricator.kde.org/D20605

To: aacid, apol
Cc: kde-frameworks-devel, michaelh, ngraham, bruns