Using compaction twice in a row in Copilot CLI results in error

[bamurtaugh]

Found while verifying #300491

If I use compaction twice in a row for a CLI session:

Using it twice in a row for local agent mode works.

[DonJayamanne]

This is an error returned from CLI, need to see what can be done, basically this happens because there's been no change since the last compaction request, hence its a noop and we're getting an error from CLI.

Will ask for changes from CLI,
Perhaps a work around for now is for us to swallow this error and display same message compacted conversation

[vs-code-engineering]

Sharing media from merged PR #311805 for verification:

Source PR: #311805