Filip Roséen authored Sep 19, 2016 and Hugo Beauzée-Luyssen committed Sep 20, 2016

The previous implementation assumed that an attribute would always
have at least one specified region/style, which is not always the
case.

An attribute's value of zero-length, or one that contains only spaces,
would make strtok_r return NULL - resulting in undefined-behavior
further down the road.

In order to prevent these issues, an additional branch has been
introduced to warn if such attributes are found, and simply ignore
them.

fixes #17405

Signed-off-by: Hugo Beauzée-Luyssen <hugo@beauzee.fr>