SW-17630 - fix a php notice if no child menus are present
SW-17630 - fix a php notice if no child menus are present

closes https://github.com/shopware/shopware/pull/938

k10r/shopware,wolv-dev/shopware,NetInventors/shopware,JonidBendo/shopware,s-haase/shopware,oktupol/shopware,JonidBendo/shopware,jhit/shopware,s-haase/shopware,s-haase/shopware,JonidBendo/shopware,jochenmanz/shopware,JonidBendo/shopware,mreiss/shopware,simkli/shopware,jhit/shopware,jhit/shopware,egoistIT/shopware,JonidBendo/shopware,egoistIT/shopware,NetInventors/shopware,mreiss/shopware,jhit/shopware,simkli/shopware,k10r/shopware,philippmahlow/shopware,philippmahlow/shopware,wolv-dev/shopware,wolv-dev/shopware,egoistIT/shopware,wolv-dev/shopware,philippmahlow/shopware,s-haase/shopware,jochenmanz/shopware,philippmahlow/shopware,NetInventors/shopware,k10r/shopware,NetInventors/shopware,mreiss/shopware,oktupol/shopware,jochenmanz/shopware,wolv-dev/shopware,jochenmanz/shopware,mreiss/shopware,NetInventors/shopware,simkli/shopware,egoistIT/shopware,k10r/shopware,s-haase/shopware,oktupol/shopware,jochenmanz/shopware,mreiss/shopware,k10r/shopware,egoistIT/shopware,oktupol/shopware,jhit/shopware,simkli/shopware,simkli/shopware,philippmahlow/shopware,oktupol/shopware