cylindrical_gear.py ValueError: Cannot build face(s): outer wire is not closed

I am trying to run the example code from the cylindrical_gear.py but get the error as below, if there is any solution I can solve this and make it start running?:

Using port 3939 taken from config file
Jupyter console not installed
Traceback (most recent call last):
File "/Users/zihan/Desktop/LLM4CAD/Dataset/IncorrectExamples/cylindrical_gear.py", line 135, in
gear2 = cylindrical_gear(m,z2,alpha,b).val().move(cq.Location(cq.Vector(m*z1/2+m*z2/2,0,0)))
File "/Users/zihan/Desktop/LLM4CAD/Dataset/IncorrectExamples/cylindrical_gear.py", line 103, in cylindrical_gear
teeths = teeths.extrude(b)
File "/Users/zihan/miniconda3/envs/ml4t/lib/python3.10/site-packages/cadquery/cq.py", line 3149, in extrude
r = self._extrude(until, both=both, taper=taper, upToFace=None)
File "/Users/zihan/miniconda3/envs/ml4t/lib/python3.10/site-packages/cadquery/cq.py", line 3782, in _extrude
faces = self._getFaces()
File "/Users/zihan/miniconda3/envs/ml4t/lib/python3.10/site-packages/cadquery/cq.py", line 3730, in _getFaces
rv.extend(wiresToFaces(self.ctx.popPendingWires()))
File "/Users/zihan/miniconda3/envs/ml4t/lib/python3.10/site-packages/cadquery/occ_impl/shapes.py", line 4167, in wiresToFaces
return Face.makeFromWires(wireList[0], wireList[1:]).Faces()
File "/Users/zihan/miniconda3/envs/ml4t/lib/python3.10/site-packages/cadquery/occ_impl/shapes.py", line 2856, in makeFromWires
raise ValueError("Cannot build face(s): outer wire is not closed")
ValueError: Cannot build face(s): outer wire is not closed