Encapsulated throw from C++ to a return false in the "C" function

Change-Id: I2fc89b0dcf434395859300b3d3890247d1288295
Reviewed-on: https://gerrit.libreoffice.org/19872Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Norbert Thiebaud <nthiebaud@gmail.com>