fix(copyCommand): provide friendlier error messages for /copy command (#6723)

Co-authored-by: Ben Guo <hundunben@gmail.com>
Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>
Co-authored-by: Jacob Richman <jacob314@gmail.com>

packages/cli/src/ui/commands/copyCommand.ts

@@ -53,7 +53,7 @@ export const copyCommand: SlashCommand = {
         return {
           type: 'message',
           messageType: 'error',
-          content: 'Failed to copy to the clipboard.',
+          content: `Failed to copy to the clipboard. ${message}`,
         };
       }
     } else {