Error when running in Ubuntu

[godadada]

Please advice how to resolve the following issue in running the tutorial:

[Thu Apr 26 2018 08:05:55 GMT-0700 (PDT)] "GET /" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/66.0.3359.117 Safari/537.36"
[Thu Apr 26 2018 08:05:55 GMT-0700 (PDT)] "GET /build/bundle.js" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/66.0.3359.117 Safari/537.36"
[Thu Apr 26 2018 08:05:55 GMT-0700 (PDT)] "GET /rust_wasm_webpack_tutorial.wasm" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/66.0.3359.117 Safari/537.36"
[Thu Apr 26 2018 08:05:55 GMT-0700 (PDT)] "GET /rust_wasm_webpack_tutorial.wasm" Error (404): "Not found"
[Thu Apr 26 2018 08:05:55 GMT-0700 (PDT)] "GET /rust_wasm_webpack_tutorial.wasm" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/66.0.3359.117 Safari/537.36"
[Thu Apr 26 2018 08:05:55 GMT-0700 (PDT)] "GET /rust_wasm_webpack_tutorial.wasm" Error (404): "Not found"

[manuel-rubio]

I've the same problem building in Mac (macOS Mojave).