Return from the method when execution the preprocessing application fails.
Return from the method when execution the preprocessing application fails.

That fixes #87941

CCMAIL:87941-done@bugs.kde.org

svn path=/trunk/kdepim/; revision=342625

lefou/kdepim-noakonadi,lefou/kdepim-noakonadi,lefou/kdepim-noakonadi,lefou/kdepim-noakonadi,lefou/kdepim-noakonadi,lefou/kdepim-noakonadi