InstallHandler isn't run on Scratch Org setup, but it should be, to properly reflect Package Production and Feeder org conditions.
*Impacts*
Unknown, impacts not yet observed
_Setup Time:_
_Error-prone?:_
_Dev/Testing Time:_
_Other impacts:_ The Custom Setting {{aduro\_\_MassDownloadSettings\_\_c}} is meant to be populated by this, as is the scheduling of the {{RollupSummaries}} job (used for calculating rollups over lookup relationships), as well as the {{Xero Sync}} job, and the {{Mass Download Cleanup}} job. These being missing has not yet impacted testing, as these are not heavily used/crucial parts of the app.
*Fix Time Estimation:*
A couple of hours of dev and testing
We need to find a way to run {{AduroInstallHandler.firstTimeInstall()}}, but this is currently private however, with no public/global references that will allow us to fire it anonymously. Simplest solution is to add a public method to InstallHandler which thinly wraps the {{firstTimeInstall}} method, perhaps with a String override code that’s required, to prevent accidental calling.