Memory leak when deleting from a locked dictionary thing implementation

[joente]

Describe the bug
When a lock is set on a dictionary implementation of a thing, a delete of a value raises an error (correctly) but also creates a memory leak.

To Reproduce
Code to reproduce the memory leak:

.set('non name key', nil);  // force a dictionary implementation
.arr = ['a', 'b'];
.arr.push({
  // push `c` but also delete the array.
  // the array is locked by the `push()` function and this correctly raises an error
  // but it also creates a memory leak as the value IS popped from the dict.
  .del('arr'); 'c'; 
});

Expected behavior
The error is correct, but it should not create a memory leak.

[joente]

Fixed in v1.1.1-rc0