I keep receiving "X ERROR - unsupported types for _ and _: 'function', 'int' " on my M5Fire for the following code. Sometimes it happens right away, other times it works flawlessly for a little while and then I get the error. Can anyone help with this?

from m5stack import *
from m5ui import *
from uiflow import *
import unit

setScreenColor(0x222222)
relay0 = unit.get(unit.RELAY, unit.PORTB)
rfid2 = unit.get(unit.RFID, unit.PORTA)

label1 = M5TextBox(253, 42, "ID:", lcd.FONT_DejaVu24,0xFFFFFF, rotate=90)
label2 = M5TextBox(297, 42, "-", lcd.FONT_DejaVu24,0xFFFFFF, rotate=90)
title = M5Title(title="Workshop", x=7 , fgcolor=0x000000, bgcolor=0xfefefe)
label4 = M5TextBox(253, 83, "-", lcd.FONT_DejaVu24,0xFFFFFF, rotate=90)

while True:
relay0.off()
label4.setText(str(rfid2.readUid()))
label2.setColor(0xcccccc)
label2.setText('Place ID Card')
while rfid2.isCardOn():
label4.setText(str(rfid2.readUid()))
if (rfid2.readUid()) == '8848f1f1c':
label2.setColor(0x33ff33)
label2.setText('Proceed')
relay0.on()
else:
label2.setColor(0xff0000)
label2.setText('Access Denied!')
break
wait_ms(2)