assistant: Improve discoverability of slash command errors (#13331)

https://github.com/zed-industries/zed/assets/53836821/fca5deef-3a4b-4670-8b92-79f052ea8417



Release Notes:

- N/A
2c545ce0bcBennet Bo Fenner committed on 6/20/2024, 7:39:53 PM· committed by GitHubparent58e9952
1 file changedLine totals unavailable