Pi freezes when running a script

Question

I'm trying to set up a trap camera using a brand new Pi Zero W with Raspbian Buster but it freezes when I run the python scirpt.

originally the code was a bit complicated with multithreading, email sending, h264 to mp4 video converting etc., but now I simplified it to find out the problem:

from gpiozero import MotionSensor
from picamera import PiCamera
from time import time
from time import sleep
from datetime import datetime

pir = MotionSensor(26)
camera=PiCamera()
camera.start_preview()
sleep(2)

while True:
        camera.resolution=(2592,1944)
        print('wait for motion')
        pir.wait_for_motion()
        print('motion detected')
        now=datetime.now().strftime('%Y%m%d_%H%M%S')
        camera.capture('/home/pi/Desktop/TRAP/'+now+'.jpg',quality=100)
        print('frame captured')
        pir.wait_for_no_motion()
        print('motion ended')
        camera.resolution=(1920,1080)

when I run it, it works for some iteration and then it freezes:

• I can still see the camera preview
  
• the clock is stopped
  
• last output is "wait for motion"
  
• sometimes a 0 bytes file is created
  

I think the problem is in the camera because if I comment the capture row it works normally