Why did this error occur while using tts api?

I would like to use TTS.
So I followed to run the service.
There is an error as below.

So I followed the error output part while looking at the "com.webos.service.tss" source code, and there was one of several clues.
Errors can be output when there is no language for TTS.

So, as in the picture below, I checked the list of languages currently available through the command and found nothing available.

Can you tell me how to solve it?

software version : webOS OSE 2.4g
hardware : raspberyPi 4

Hi @SSo,

I tested it but I got a different result as shown below.
Could you share your steps in detail?
ps) I used OSE 2.5.0.

root@raspberrypi4:/etc/google# luna-send -n 1 -f luna://com.webos.service.tts/ge
tAvailableLanguages '{}'
    "Languages": [
    "returnValue": true