Custom Local Addon installation fail

recently i decided to write a custom addon, i followed the initial steps from here, everything working fine up till the step where i want to install the addon once i click on the install button i get the (failed to install the Addon, Unknown Error, see supervisor), when i check the supervisor logs it shows one line related to this error (21-07-22 15:15:00 ERROR (SyncWorker_5) [supervisor.docker.addon] Invalid build environment, can’t build this add-on!)

I am using Home Assistant OS on RP4 everything is up to date