demuxUsm status code

[SuperZombi]

demuxUsm command returns status 0 even if an error occurred.

process = subprocess.Popen([SCRIPT_FILE, 'demuxUsm', file, '--output', OUTPUT_F], stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
p_status = process.wait()
print("STATUS", p_status)

Finding encryption key for Cs_Liyue_EQ401860901_HDJ1.usm...
System.Collections.Generic.KeyNotFoundException: Unable to find the second key in versions.json for Cs_Liyue_EQ401860901_HDJ1
STATUS 0

If the access key is not found, I expect to receive a status code not equal to 0.