Unable to send empty or non-JSON payload in command

[ctron]

Trying to send a command without payload:

➜  drg cmd test1 "foo" --application ctron
error: The following required arguments were not provided:
    <--payload <payload>|--filename <FILE>>

USAGE:
    drg command --application <applicationId> <--payload <payload>|--filename <FILE>> <deviceId> <command>

For more information try --help

Trying to send a command with a non-JSON payload:

➜  drg cmd test1 "foo" --application ctron --payload ""
Error: Can't parse data args: '' into json

Caused by:
    EOF while parsing a value at line 1 column 0