fix: remove fixup ending tag

[abeatrix]

Close #114

This is a quick temporary fix for the issue where fixup replacement contains </selection> tag at the end:

This fix is served as a temporary fix as Dom's PR #70 to improve the multiplexer should fix this issue properly.
Adding this line of code however, could use as a fallback in the future and should not break anything before and after Dom's PR:

Also added error handling to surface error messages during the inline fixup step.

Notes

Looks like the issue was a regression from sourcegraph/sourcegraph#54665 as this issue does not exist when switching to the previous version (0.4.2). As the response is now being streamed to Inline Chat, caused the result to be sent to the multiplexer before the turn is marked as completed.

Test Plan

1. Start Cody from this branch
2. Perform a Inline Fixup
3. Check if the fixup result includes the </selection> at the end

[chrispine]

Thanks for this fix! I don't know enough about the code to feel confident to approve it, but I did have a few comments.

[st0nebreaker]

Groovy! LGTM