Manage .unwrap_or_else closures properly to report user's call location in case of panic

Author: rakivo

src/map.rs

@@ -1474,14 +1474,14 @@ impl<K, V, S> Index<usize> for IndexMap<K, V, S> {
     ///
     /// ***Panics*** if `index` is out of bounds.
     fn index(&self, index: usize) -> &V {
-        self.get_index(index)
-            .unwrap_or_else(|| {
-                panic!(
-                    "index out of bounds: the len is {len} but the index is {index}",
-                    len = self.len()
-                );
-            })
-            .1
+        if let Some((_, value)) = self.get_index(index) {
+            value
+        } else {
+            panic!(
+                "index out of bounds: the len is {len} but the index is {index}",
+                len = self.len()
+            );
+        }
     }
 }
 
@@ -1521,11 +1521,11 @@ impl<K, V, S> IndexMut<usize> for IndexMap<K, V, S> {
     fn index_mut(&mut self, index: usize) -> &mut V {
         let len: usize = self.len();
 
-        self.get_index_mut(index)
-            .unwrap_or_else(|| {
-                panic!("index out of bounds: the len is {len} but the index is {index}");
-            })
-            .1
+        if let Some((_, value)) = self.get_index_mut(index) {
+            value
+        } else {
+            panic!("index out of bounds: the len is {len} but the index is {index}");
+        }
     }
 }
 

src/set.rs

@@ -1106,12 +1106,14 @@ impl<T, S> Index<usize> for IndexSet<T, S> {
     ///
     /// ***Panics*** if `index` is out of bounds.
     fn index(&self, index: usize) -> &T {
-        self.get_index(index).unwrap_or_else(|| {
+        if let Some(value) = self.get_index(index) {
+            value
+        } else {
             panic!(
                 "index out of bounds: the len is {len} but the index is {index}",
                 len = self.len()
             );
-        })
+        }
     }
 }