gh-131798: Use sym_new_type instead of sym_new_not_null for _BUILD_STRING, _BUILD_SET

Misc/NEWS.d/next/Core_and_Builtins/2025-04-26-18-43-31.gh-issue-131798.FsIypo.rst

@@ -0,0 +1,2 @@
+Use ``sym_new_type`` instead of ``sym_new_not_null`` for _BUILD_STRING,
+_BUILD_SET

Python/optimizer_bytecodes.c

@@ -977,6 +977,14 @@ dummy_func(void) {
         map = sym_new_type(ctx, &PyDict_Type);
     }
 
+    op(_BUILD_STRING, (values[oparg] -- str)) {
+        str = sym_new_type(ctx, &PyUnicode_Type);
+    }
+
+    op(_BUILD_SET, (values[oparg] -- set)) {
+        set = sym_new_type(ctx, &PySet_Type);
+    }
+
     op(_UNPACK_SEQUENCE_TWO_TUPLE, (seq -- val1, val0)) {
         val0 = sym_tuple_getitem(ctx, seq, 0);
         val1 = sym_tuple_getitem(ctx, seq, 1);