text: Replace some more release panics with graceful fallbacks (#44542)

Fixes ZED-3P7

Release Notes:

- N/A *or* Added/Fixed/Improved ...

crates/text/src/text.rs

@@ -39,6 +39,7 @@ pub use subscription::*;
 pub use sum_tree::Bias;
 use sum_tree::{Dimensions, FilterCursor, SumTree, TreeMap, TreeSet};
 use undo_map::UndoMap;
+use util::debug_panic;
 
 #[cfg(any(test, feature = "test-support"))]
 use util::RandomCharIter;
@@ -2439,7 +2440,7 @@ impl BufferSnapshot {
         if bias == Bias::Left && offset == 0 {
             Anchor::min_for_buffer(self.remote_id)
         } else if bias == Bias::Right
-            && ((cfg!(debug_assertions) && offset >= self.len()) || offset == self.len())
+            && ((!cfg!(debug_assertions) && offset >= self.len()) || offset == self.len())
         {
             Anchor::max_for_buffer(self.remote_id)
         } else {
@@ -2453,7 +2454,15 @@ impl BufferSnapshot {
                 };
             }
             let (start, _, item) = self.fragments.find::<usize, _>(&None, &offset, bias);
-            let fragment = item.unwrap();
+            let Some(fragment) = item else {
+                // We got a bad offset, likely out of bounds
+                debug_panic!(
+                    "Failed to find fragment at offset {} (len: {})",
+                    offset,
+                    self.len()
+                );
+                return Anchor::max_for_buffer(self.remote_id);
+            };
             let overshoot = offset - start;
             Anchor {
                 timestamp: fragment.timestamp,