[18.0][FIX] hr_shift: reduce crash when missing data#26

OCA-git-bot merged 2 commits intoOCA:18.0OCA/shift-planning:18.0from

TechnoLibre:18.0_hr_shift_fix_first_executionTechnoLibre/oca-shift-planning:18.0_hr_shift_fix_first_executionCopy head branch name to clipboard