SqlSetup: Error message is cryptic when Test-TargetResource returns false when called from Set-TargetResource

Details of the scenario you tried and the problem that is occurring:

This error message is kind of cryptic for users not familiar with the code.

Test-TargetResource returned false after calling Set-TargetResource. 

A more correct message could be:

Set-TargetResource tried to certify the configuration state with Test-TargetResource, but verification failed. Test-TargetResource returned false (not in desired state).

The DSC configuration that is using the resource (as detailed as possible):
Any xSQLServerSetup that fail configuration (for example setup.exe returns with an error).

Version of the Operating System, SQL Server and PowerShell the DSC Target Node is running:
n/a

What module (SqlServer or SQLPS) and which version of the module the DSC Target Node is running:
n/a

Version of the DSC module you're using, or 'dev' if you're using current dev branch:
Dev

Locate the SqlSetup resource code that emits "Test-TargetResource returned false after calling Set-TargetResource." Start by tracing the Set-TargetResource verification path and update the failure wording to explain that verification failed and the configuration is not in the desired state. Confirm the revised message covers failed xSQLServerSetup configurations.