I run a Odoo 12 Community server on my Windows 10 PC, then I install MuK Documents and MuK Preview modules (which downloaded from apps store).

When I click Preview button in PDF document, the preview popup showed without error, but no file loaded, and the browser console log got problem

Refused to execute script from 'http://localhost:8069/web/static/lib/pdfjs/src/shared/util.js' because its MIME type ('text/plain') is not executable.

Uncaught DOMException: Failed to execute 'importScripts' on 'WorkerGlobalScope': The script at 'http://localhost:8069/web/static/lib/pdfjs/src/shared/util.js' failed to load.
    at http://localhost:8069/web/static/lib/pdfjs/src/worker_loader.js:71:5

I thought that issue doesn't cause by the MuK modules installed, but the base web module. But I don't have any idea how to deal with it.