How js file is reserved as text/javascript

[Koyo46]

Summary

I made a project using React & Laravel .
deploy is completed, then i access the page, a blank screen appears.
there are error messages in console.

Failed to load module script: Expected a JavaScript module script but the server responded with a MIME type of "text/html". Strict MIME type checking is enforced for module scripts per HTML spec.

Example

https://septet-symphony-l10-fssbewj0z-reikens-projects.vercel.app/

Steps to Reproduce

I made a project using React & Laravel .
deploy is completed, then i access the page, a blank screen appears.
there are error messages in console.

Failed to load module script: Expected a JavaScript module script but the server responded with a MIME type of "text/html". Strict MIME type checking is enforced for module scripts per HTML spec.

I tried fix this bug with modify vercel.json.

"routes": [
        {
            "src": "/api/(.*)",
            "dest": "/api/index.php"
        },
        {
            "src": "/public/build/assets/(.*)",
            "dest": "/public/build/assets/$1",
            "headers": {
                "Content-Type": "application/javascript"
            }
        },
        {
            "src": "/(.*)",
            "dest": "/public/build/index.html",
            "headers": {
                "cache-control": "s-maxage=31536000,immutable"
            }
        }
    ],

but it dosent solved.

please help me~
I'm japanese, sorry for poor English.