Fix a panic in can_resolve when the excerpt id is unknown

Conrad Irwin created 1 month ago

Cherry-pick of #50052

Change summary

crates/multi_buffer/src/multi_buffer.rs | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)

Detailed changes

crates/multi_buffer/src/multi_buffer.rs

@@ -6847,18 +6847,23 @@ impl MultiBufferSnapshot {
     }
 
     fn excerpt_locator_for_id(&self, id: ExcerptId) -> &Locator {
+        self.try_excerpt_locator_for_id(id)
+            .unwrap_or_else(|| panic!("invalid excerpt id {id:?}"))
+    }
+
+    fn try_excerpt_locator_for_id(&self, id: ExcerptId) -> Option<&Locator> {
         if id == ExcerptId::min() {
-            Locator::min_ref()
+            Some(Locator::min_ref())
         } else if id == ExcerptId::max() {
-            Locator::max_ref()
+            Some(Locator::max_ref())
         } else {
             let (_, _, item) = self.excerpt_ids.find::<ExcerptId, _>((), &id, Bias::Left);
             if let Some(entry) = item
                 && entry.id == id
             {
-                return &entry.locator;
+                return Some(&entry.locator);
             }
-            panic!("invalid excerpt id {id:?}")
+            None
         }
     }
 
@@ -6944,7 +6949,7 @@ impl MultiBufferSnapshot {
     fn excerpt(&self, excerpt_id: ExcerptId) -> Option<&Excerpt> {
         let excerpt_id = self.latest_excerpt_id(excerpt_id);
         let mut cursor = self.excerpts.cursor::<Option<&Locator>>(());
-        let locator = self.excerpt_locator_for_id(excerpt_id);
+        let locator = self.try_excerpt_locator_for_id(excerpt_id)?;
         cursor.seek(&Some(locator), Bias::Left);
         if let Some(excerpt) = cursor.item()
             && excerpt.id == excerpt_id