ProjectQ - Error messages

How can we get rid of runtime next error:

Traceback (most recent call last):
  File "C:UsersMarijaAnaconda3libsite-packagesprojectqtypes_qubit.py", line 135, in __del__
    self.engine.deallocate_qubit(weak_copy)
  File "C:UsersMarijaAnaconda3libsite-packagesprojectqcengines_basics.py", line 153, in deallocate_qubit
    tags=[DirtyQubitTag()] if is_dirty else [])])
  File "C:UsersMarijaAnaconda3libsite-packagesprojectqcengines_main.py", line 288, in send
    raise compact_exception  # use verbose=True for more info
RuntimeError: Qubit has not been measured / uncomputed. Cannot access its classical value and/or deallocate a qubit in superposition!
 raised in:
'  File "C:\Users\Marija\Anaconda3\lib\site-packages\projectq\backends\_sim\_pysim.py", line 139, in get_classical_value'
'    raise RuntimeError("Qubit has not been measured / "'```