fix(xo-server/RestApi): don't fail on missing express
fix(xo-server/RestApi): don't fail on missing express

Which is the case when instanciated from `xo-server-recover-account`.

vatesfr/xo-web,lmcro/xo-web,lmcro/xo-web,vatesfr/xo-web,lmcro/xo-web