Source files missing when running locally

When running cesium and connecting to localhost. Any app I click on has missing files. There’s an error 404 for Source/Cesium.js and in Sandcastle (the app I need it for), there’s a reference error stating VERSION is not defined in data-dojo-properties='title: ‘CESIUM ’ + VERSION’ for parser.js:899. All I’ve done is an npm i; npm run start in the master branch. I want to use localhost to test a pr I’m working on (whose branch as well as all besides master are missing even after a clean git clone, but I believe that’s a separate issue).