Fix integer underflow situation on empty lists.

bodil · Apr 6, 2018 · 901270a · 901270a
1 parent 286b270
commit 901270a
Showing 1 changed file with 5 additions and 1 deletion.
diff --git a/src/vector.rs b/src/vector.rs
@@ -206,7 +206,11 @@ impl<A> Vector<A> {
     ///
     /// Time: O(log n)
     pub fn last(&self) -> Option<Arc<A>> {
-        self.get(self.len() - 1)
+        if self.is_empty() {
+            None
+        } else {
+            self.get(self.len() - 1)
+        }
     }
 
     /// Get the vector without the last element.