Bug 26940: Take empty strings into account

Bug 26940: Take empty strings into account

Signed-off-by: Katariina Hanhisalo <katariina.hanhisalo@xamk.fi>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
(cherry picked from commit 789ddd59c92183af350eba427ad545e3dce82422)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>
(cherry picked from commit 8986198c02d024b03e33b0b4e3159401ee3ca6c3)

Signed-off-by: Andrew Fuerste-Henry <andrew@bywatersolutions.com>