TypeError: 'NoneType' object is not iterable

[davefr90]

• ModBus TCP proxy version: the last one
• Python version:
• Operating System: Rasppi2

Description

Unfortunately, when I try to start the program via the console, it doesn't work.
When I enter it using the details on the console it works great, but unfortunately it just doesn't stay active. As soon as I close the console the program apparently quits.
modbus-proxy -b tcp://192.168.2.84:9001 --modbus tcp://192.168.2.91:502 --modbus-connection-time 0.1 --timeout 15

Output of the error in the console:

return [ModBus(cfg) for cfg in config["devices"]]
TypeError: 'NoneType' object is not iterable

What I Did

What is written in the config file:

devices:
-modbus:
url: 192.168.2.91:502
timeout: 15
connection_time: 0.1
listen:
bind: 192.168.2.84:9001

I have no idea what the error is anymore, I changed every IP address, I was able to remove all TAB errors but this error remains.