[Issue] SourceSideValidations - Cannot find an overload for "op_Subtraction" and the argument count: "2".

[bill-long]

Customer reported:

.\SourceSideValidations.ps1 -RemoveInvalidPermissions
Cannot find an overload for "op_Subtraction" and the argument count: "2".
At C:\work\SourceSideValidations.ps1:2920 char:5
+     Write-Host "SourceSideValidations $BuildVersion complete. Total d ...
+     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [], MethodException
    + FullyQualifiedErrorId : MethodCountCouldNotFindBest