This problem is about memory deallocation. In Reflang, the free expression deallocates memory. The current semantics of free expression is permissive, in that it allows a memory location to be deallocated even if it has been deallocated previously.
Change the semantics of the free expression such that attempts to deallocate a value that is already allocated result in a dynamic error with the message, “Illegal deallocation of ref value loc:0.”
For example,