index setter was leaking memory

Author: lostmsu

src/runtime/Types/ClassBase.cs

@@ -497,14 +497,8 @@ static int mp_ass_subscript_impl(BorrowedReference ob, BorrowedReference idx, Bo
             // Add value to argument list
             Runtime.PyTuple_SetItem(real.Borrow(), i, v);
 
-            cls.indexer.SetItem(ob, real.Borrow());
-
-            if (Exceptions.ErrorOccurred())
-            {
-                return -1;
-            }
-
-            return 0;
+            using var result = cls.indexer.SetItem(ob, real.Borrow());
+            return result.IsNull() ? -1 : 0;
         }
 
         static NewReference tp_call_impl(BorrowedReference ob, BorrowedReference args, BorrowedReference kw)

src/runtime/Types/Indexer.cs

@@ -50,9 +50,9 @@ internal NewReference GetItem(BorrowedReference inst, BorrowedReference args)
         }
 
 
-        internal void SetItem(BorrowedReference inst, BorrowedReference args)
+        internal NewReference SetItem(BorrowedReference inst, BorrowedReference args)
         {
-            SetterBinder.Invoke(inst, args, null);
+            return SetterBinder.Invoke(inst, args, null);
         }
 
         internal bool NeedsDefaultArgs(BorrowedReference args)