Receive Join while doing other things

[fernandes.son]

Is it necessary to wait for join inside the loop with time.sleep ()? I'm just using a if to check the join but sometimes got a reset. I can't wait for join to start the system work

while():
        wdt.feed()
        do_work()
        if not lora.has_joined():
            utime.sleep(2)
        else:
            print("joined")

Guru Meditation Error: Core 1 panic'ed (Cache disabled but cached memory region accessed)
Core 1 register dump:
PC : 0x4011b148 PS : 0x00060434 A0 : 0x80085390 A1 : 0x3ffbf0b0
A2 : 0x00000002 A3 : 0x3ffca1f0 A4 : 0x00000000 A5 : 0x000956e7
A6 : 0x3ffcb24c A7 : 0x00000001 A8 : 0x8008462e A9 : 0x3ffbf090
A10 : 0x000956e7 A11 : 0x3ffbf0b1 A12 : 0x3ffbf0b1 A13 : 0x3ffcb2a8
A14 : 0x3ffcb298 A15 : 0x3ffd47f4 SAR : 0x0000000e EXCCAUSE: 0x00000007
EXCVADDR: 0x00000000 LBEG : 0x4008f0ba LEND : 0x4008f0c5 LCOUNT : 0x00000000
Core 1 was running in ISR context:
EPC1 : 0x40084157 EPC2 : 0x40211f42 EPC3 : 0x00000000 EPC4 : 0x4011b148

(sysname='LoPy4', nodename='LoPy4', release='1.20.2.rc6', version='v1.11-01f49f7 on 2020-02-28', machine='LoPy4 with ESP32', lorawan='1.0.2', sigfox='1.0.1', pybytes='1.3.1')