Add a hand-written error message for the `seek_internal` precondition

Max Brunsfeld created 4 years ago

Change summary

zed/src/sum_tree/cursor.rs | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

Detailed changes

zed/src/sum_tree/cursor.rs

@@ -413,7 +413,12 @@ where
         D: Dimension<'a, T::Summary>,
     {
         if let Some(target) = target {
-            debug_assert!(target.cmp(&self.seek_dimension, cx) >= Ordering::Equal);
+            debug_assert!(
+                target.cmp(&self.seek_dimension, cx) >= Ordering::Equal,
+                "cannot seek backward from {:?} to {:?}",
+                self.seek_dimension,
+                target
+            );
         }
 
         if !self.did_seek {