sounddevice.PortAudioError: Error opening OutputStream: Internal PortAudio error [PaErrorCode -9986] - portaudio

Question

I am on MacMojave and try to play a sound file if a microphone signal goes above a threshold. I have :
import sounddevice as sd
import soundfile as sf
import numpy as np
duration = 5 # seconds
threshold = 30
filename = "./data/piano.wav"
data, fs = sf.read(filename, dtype='float32')
def print_sound(indata, outdata, frames, time, status):
if status:
print(status)
global threshold, data, fs
volume_norm = 5*np.linalg.norm(indata)
if volume_norm > threshold:
print("so loud!!!!")
sd.play(data, fs)
with sd.Stream(callback=print_sound):
sd.sleep(1000*duration)
When I run this the sound goes above threshold, however, it cannot open the output Stream as follows;
$python3 main.py
input underflow
input underflow
input underflow
so loud!!!!
so loud!!!!
input overflow, output underflow
so loud!!!!
input overflow, output underflow
so loud!!!!
||PaMacCore (AUHAL)|| Error on line 1316: err=''nope'', msg=Audio Hardware: Illegal Operation
From cffi callback <function _StreamBase.__init__.<locals>.callback_ptr at 0x10caf8680>:
Traceback (most recent call last):
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/sounddevice.py", line 881, in callback_ptr
callback, idata, odata, frames, time, status)
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/sounddevice.py", line 2678, in _wrap_callback
callback(*args)
File "main.py", line 17, in print_sound
sd.play(data, fs)
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/sounddevice.py", line 177, in play
**kwargs)
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/sounddevice.py", line 2578, in start_stream
**kwargs)
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/sounddevice.py", line 1489, in __init__
**_remove_self(locals()))
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/sounddevice.py", line 895, in __init__
'Error opening {}'.format(self.__class__.__name__))
File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/sounddevice.py", line 2738, in _check
raise PortAudioError(errormsg, err)
sounddevice.PortAudioError: Error opening OutputStream: Internal PortAudio error [PaErrorCode -9986]
I have restarted my iMac ( Mojave) and still get the same error.
Any help would be much appreciated.
CS