bug fix: Eff=1 => crash

After re-indexing the whole 2022 year, I've encountered a few crashes happening during February, March, May and July. After studying the problem I found out that they were related to having no BusyRates entries for some LBs. This is due to to having no busy detector during that particular LB but the app was always expecting a BusyRate entry so it crashed. This is now fixed and this occurrence is handled by giving the LB an efficiency of 1 and having no busy entries in the output. It does not mean that also no hold trigger happened during the LB, but the Eff entry in the output only refers to busy inefficiency, as it did in the old app.