fix crash when m_aType is '*'

Change-Id: If2c4ca98814a58b785cd2670eac1e522e70464fd
(cherry picked from commit 5983675eccd9517915d8f5558c25f47c952edb24)
Reviewed-on: https://gerrit.libreoffice.org/10048
Tested-by: Markus Mohrhard <markus.mohrhard@googlemail.com>
Reviewed-by: Markus Mohrhard <markus.mohrhard@googlemail.com>