fix(ai-prompt-template): fix malformed JSON error message

[sihyeonn]

Description

The error message in get_request_body_table() had two issues:

1. Grammatical error: "could not get parse" instead of "could not parse"
2. String concatenation bug: err was added as a separate table element ({ message = "...: ", err }) instead of being concatenated to the message string ({ message = "...: " .. err }), causing the error detail to be silently dropped from the response.

The correct pattern already exists in ai-prompt-decorator.lua:76.

Before

return nil, { message = "could not get parse JSON request body: ", err }

After

return nil, { message = "could not parse JSON request body: " .. err }

[Baoyuantop]

Please update the code in all relevant places.

[Baoyuantop]

Hi @sihyeonn, following up on the previous review comments. Please let us know if you have any updates. Thank you.

[sihyeonn]

Hi, thanks for the follow-up. The fix has been applied — the error message now correctly reflects the malformed JSON case. Ready for review whenever you get a chance.

[Baoyuantop]

Hi @sihyeonn, I mean, there are several similar errors; could you fix them all at once?