AttributeError TerraSAR data process using stackStripMap.py

[wandi12345]

I have already processed TerraSAR using unpackFrame_TSX.py.
but, when I run stackStripMap.py -s /misc/test/slc/ -d /misc/test/DEM/demLat_N28_N31_Lon_E108_E111.dem.wgs84 -t 120 -b 400 -a 1 -r 2 -m 20210306 -W slc -u snaphu --nofocus --zero
I got an error like this
Traceback (most recent call last):
File "/misc/isce2/contrib/stack/stripmapStack/stackStripMap.py", line 363, in
main()
File "/misc/isce2/contrib/stack/stripmapStack/stackStripMap.py", line 333, in main
if inps.sensor.lower() == 'uavsar_stack': # don't try to calculate baselines for UAVSAR_STACK data
AttributeError: 'NoneType' object has no attribute 'lower'
I have no idea how to debug.