Heroku app crashes when attempting to upgrade to newer v6

I am currently running the 6.3.3 Docker image on Heroku. When updating to a newer version, the app crashes with the following error:

{
    "name": "coral",
    "hostname": "90da815c-79b7-42d5-9f31-a4a5dc6a81e0",
    "pid": 3,
    "level": 50,
    "err": {
        "message": "invalid language code: .wh..wh..opq",
        "name": "Error",
        "stack": "I18n.load (src/core/server/services/i18n/index.ts:47:17)\nServer.connect (src/core/server/index.ts:221:5)\nbootstrap (src/index.ts:51:5)\n"
    },
    "msg": "can not bootstrap server",
    "time": "2021-08-24T20:06:38.634Z",
    "src": {
        "file": "/usr/src/app/src/index.ts",
        "line": 59,
        "func": "bootstrap"
    },
    "v": 0
}

In an attempt to narrow things down, I have tried 6.13.2, 6.10.0, and 6.9.1, which crash; and 6.8.1, 6.7.2, and 6.3.12, which do not crash. I am deploying according to Heroku's instructions, e.g.:

heroku container:login
docker pull coralproject/talk:6.13.2
docker tag coralproject/talk:6.13.2 registry.heroku.com/<app>/web
docker push registry.heroku.com/<app>/web
heroku container:release web --app=<app>

The error seems to point to an issue with Heroku's filesystem not liking the ../../.. parent directory iteration of locales, but beyond that conclusion I'm a bit lost for how it could be resolved. Any insights?

Expected behavior: Upgrading to a newer version of Coral on Heroku is successful.

Actual behavior: Heroku app crashes.

Related Issues: None

Versions:

NodeJS: 12
NPM:
MongoDB: 4.4.8
Redis: 6.0.9
Browser:
OS:

coralproject / talk

Heroku app crashes when attempting to upgrade to newer v6 #3680