if (a == NULL || a->b == NULL)
leads to a NULL pointer dereference if a == NULL.
Reviewed-by: NChristian König <christian.koenig@amd.com>
Signed-off-by: NHeinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>