[powershell] Powershell: A positional parameter cannot be found that accepts argument "xxx"

In my case it was the distinction between (En dash) and -(Hyphen) as in:

Add-Type –Path "C:\Program Files\Common Files\microsoft shared\Web Server Extensions\16\ISAPI\Microsoft.SharePoint.Client.dll"

and:

Add-Type -Path "C:\Program Files\Common Files\microsoft shared\Web Server Extensions\16\ISAPI\Microsoft.SharePoint.Client.dll"

Dashes, Hyphens, and Minus signs oh my!