basic: _FIND_STATIC likely not an error in SbiExprNode::GenElement()

All other _FIND_* are explicitly not errors, and probably CWS npower10
forgot to adapt this assertion.

Change-Id: If721c275eb1bc31d76140898602b41e11c23d82e
Reviewed-on: https://gerrit.libreoffice.org/7863
Reviewed-by: Noel Power <noel.power@suse.com>
Tested-by: Noel Power <noel.power@suse.com>