About HTTPClient.wrapError for LINEBOT that functions, hosting in firebase.

Currently, I am trying to build LINE messaging API by functioning and hosting on firebase, but the callback on the webbook is 400 errors.But for some reason, they only return text message replies.
However, when it comes to the reply of flexMessage, I cannot come back because of an error.
The fireaseFunctions error codes are as follows:

Error: Request failed with status code 400
    at HTTPClient.wrapError (/srv/node_modules/@line/bot-sdk/dist/http.js:83:20)
    at HTTPClient.instance.interceptors.response.use.err(/srv/node_modules/@line/bot-sdk/dist/http.js:19:88)
    at<anonymous>
    at process._tickDomainCallback (internal/process/next_tick.js:229:7)

By the way, I tried to modify @line/bot-sdk/http.js by referring to the site below, but it didn't work.
I would appreciate it if someone could let me know.

Linebot To Move -Qiita