[Repo Assist] fix: use NotSupportedException in CombinedStream; clarify inner isText#1695

dsyme merged 2 commits intomainfsprojects/FSharp.Data:mainfrom

repo-assist/improve-http-stream-exceptions-20260314-a24c76554c4a3c14fsprojects/FSharp.Data:repo-assist/improve-http-stream-exceptions-20260314-a24c76554c4a3c14Copy head branch name to clipboard