From 68994248ee31adb11a0d5844c92620b89ae5bc09 Mon Sep 17 00:00:00 2001
From: Max Brunsfeld <maxbrunsfeld@gmail.com>
Date: Wed, 2 Jun 2021 17:47:25 -0700
Subject: [PATCH] Add custom error message for rope cursor slice precondition

---
 zed/src/editor/buffer/rope.rs | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/zed/src/editor/buffer/rope.rs b/zed/src/editor/buffer/rope.rs
index 05b30e3896..1b5d8fb896 100644
--- a/zed/src/editor/buffer/rope.rs
+++ b/zed/src/editor/buffer/rope.rs
@@ -213,7 +213,12 @@ impl<'a> Cursor<'a> {
     }
 
     pub fn slice(&mut self, end_offset: usize) -> Rope {
-        debug_assert!(end_offset >= self.offset);
+        debug_assert!(
+            end_offset >= self.offset,
+            "cannot slice backwards from {} to {}",
+            self.offset,
+            end_offset
+        );
 
         let mut slice = Rope::new();
         if let Some(start_chunk) = self.chunks.item() {