show count of corrupted media keys in delete-remote-media command

src/service/admin.rs

@@ -806,8 +806,10 @@ impl Service {
                     }
                 });
 
+                let mut failed_keys = 0;
                 while let Some(mxc) = rx.recv().await {
                     let Ok(mxc) = mxc else {
+                        failed_keys += 1;
                         continue;
                     };
 
@@ -828,11 +830,25 @@ impl Service {
                     }
                 }
 
-                let message = if dry_run {
+                let mut message = if dry_run {
                     format!("{count} media objects would be deleted.")
                 } else {
                     format!("{count} media objects deleted.")
                 };
+
+                if failed_keys != 0 {
+                    write!(
+                        message,
+                        "\n{failed_keys} corrupted media keys found in the \
+                         database."
+                    )
+                    .unwrap();
+                    write!(
+                        message,
+                        "\nCheck the server logs for more details."
+                    )
+                    .unwrap();
+                }
                 RoomMessageEventContent::text_plain(message)
             }
             AdminCommand::DeactivateUser {