Problems with the __del__ magic command in Xfoil

[emvalbuena]

While running in a notebook, after going through an optimization routine, this output came out.

Exception ignored in: <bound method XFoil.__del__ of <xfoil.xfoil.XFoil object at 0x12e0c54a8>>
Traceback (most recent call last):
  File "/Users/Kike/Library/Mobile Documents/com~apple~CloudDocs/Documents/Inbox/TU_Delft/MsC/Q1/Aircraft_Aerodynamics/Code/xfoil-python/src/xfoil/xfoil.py", line 78, in __del__
    handle = self._lib._handle
AttributeError: 'XFoil' object has no attribute '_lib'