Unable to load valid module manifest data

When trying to install the module, either through the browser or directly by URL I get the error "Unable to load valid module manifest data".

Error: Unable to load valid module manifest data from "https://gitlab.com/pearcebasmanm/rule-element-generator/-/raw/main/module.json"
Module Model Validation Errors
[Module.languages]: Model Validation Errors
Model Validation Errors
[lang]: Incorrect locale information provided
    at Module.installPackage (/home/squirrel/foundryvtt/resources/app/dist/packages/views.mjs:1:1620)
    at processTicksAndRejections (internal/process/task_queues.js:95:5)
    at async SetupView.handlePost (/home/squirrel/foundryvtt/resources/app/dist/server/views/setup.mjs:1:1980)