fix: fail checkheader if 0 files are checked
fix: fail checkheader if 0 files are checked

Signed-off-by: campionfellin <0acbbe3edde3b639e15eb62c8f1cc988b649aa40@gmail.com>

OpenEnergyDashboard/OED,OpenEnergyDashboard/OED,OpenEnergyDashboard/OED,OpenEnergyDashboard/OED