The Blazor Demo has a missing component.
When you follow the steps for the blazor demo (https://pdfjs.express/documentation/get-started/blazor/new-project). When you view the webviewer page you are presented an exception that “Microsoft.JSInterop.JSException: WebViewer is not defined”.
To fix I had to manually add “webviewer.min.js” to the lib directory.
It works for me now but thought others might have the same issue.