Fix invalid memory read in the ENTER_EXECUTOR

Author: sergey-miryanov

Python/bytecodes.c

@@ -3018,7 +3018,7 @@ dummy_func(
                 goto stop_tracing;
             }
             PyCodeObject *code = _PyFrame_GetCode(frame);
-            _PyExecutorObject *executor = code->co_executors->executors[oparg & 255];
+            _PyExecutorObject *executor = code->co_executors->executors[this_instr->op.arg];
             assert(executor->vm_data.index == INSTR_OFFSET() - 1);
             assert(executor->vm_data.code == code);
             assert(executor->vm_data.valid);