npx: Failed to decode param '/%PUBLIC_URL%/favicon.ico'

[andys8]

Is this a bug report?

Yes. When trying to use create-elm-app with npx, it failed with url resolution for string replacement of favicon and manifest.

URIError: Failed to decode param '/%PUBLIC_URL%/favicon.ico'
    at decodeURIComponent (<anonymous>)
    at decode_param (/home/as/.npm/_npx/22659/lib/node_modules/elm-app/node_modules/express/lib/router/layer.js:172:12)
    at Layer.match (/home/as/.npm/_npx/22659/lib/node_modules/elm-app/node_modules/express/lib/router/layer.js:123:27)
    at matchLayer (/home/as/.npm/_npx/22659/lib/node_modules/elm-app/node_modules/express/lib/router/index.js:574:18)
    at next (/home/as/.npm/_npx/22659/lib/node_modules/elm-app/node_modules/express/lib/router/index.js:220:15)
    at expressInit (/home/as/.npm/_npx/22659/lib/node_modules/elm-app/node_modules/express/lib/middleware/init.js:40:5)
    at Layer.handle [as handle_request] (/home/as/.npm/_npx/22659/lib/node_modules/elm-app/node_modules/express/lib/router/layer.js:95:5)
    at trim_prefix (/home/as/.npm/_npx/22659/lib/node_modules/elm-app/node_modules/express/lib/router/index.js:317:13)
    at /home/as/.npm/_npx/22659/lib/node_modules/elm-app/node_modules/express/lib/router/index.js:284:7
    at Function.process_params (/home/as/.npm/_npx/22659/lib/node_modules/elm-app/node_modules/express/lib/router/index.js:335:12)
    at next (/home/as/.npm/_npx/22659/lib/node_modules/elm-app/node_modules/express/lib/router/index.js:275:10)
    at query (/home/as/.npm/_npx/22659/lib/node_modules/elm-app/node_modules/express/lib/middleware/query.js:45:5)
    at Layer.handle [as handle_request] (/home/as/.npm/_npx/22659/lib/node_modules/elm-app/node_modules/express/lib/router/layer.js:95:5)
    at trim_prefix (/home/as/.npm/_npx/22659/lib/node_modules/elm-app/node_modules/express/lib/router/index.js:317:13)
    at /home/as/.npm/_npx/22659/lib/node_modules/elm-app/node_modules/express/lib/router/index.js:284:7
    at Function.process_params (/home/as/.npm/_npx/22659/lib/node_modules/elm-app/node_modules/express/lib/router/index.js:335:12)
URIError: Failed to decode param '/%PUBLIC_URL%/manifest.json'
    at decodeURIComponent (<anonymous>)
    at decode_param (/home/as/.npm/_npx/22659/lib/node_modules/elm-app/node_modules/express/lib/router/layer.js:172:12)
    at Layer.match (/home/as/.npm/_npx/22659/lib/node_modules/elm-app/node_modules/express/lib/router/layer.js:123:27)
    at matchLayer (/home/as/.npm/_npx/22659/lib/node_modules/elm-app/node_modules/express/lib/router/index.js:574:18)
    at next (/home/as/.npm/_npx/22659/lib/node_modules/elm-app/node_modules/express/lib/router/index.js:220:15)
    at expressInit (/home/as/.npm/_npx/22659/lib/node_modules/elm-app/node_modules/express/lib/middleware/init.js:40:5)
    at Layer.handle [as handle_request] (/home/as/.npm/_npx/22659/lib/node_modules/elm-app/node_modules/express/lib/router/layer.js:95:5)
    at trim_prefix (/home/as/.npm/_npx/22659/lib/node_modules/elm-app/node_modules/express/lib/router/index.js:317:13)
    at /home/as/.npm/_npx/22659/lib/node_modules/elm-app/node_modules/express/lib/router/index.js:284:7
    at Function.process_params (/home/as/.npm/_npx/22659/lib/node_modules/elm-app/node_modules/express/lib/router/index.js:335:12)
    at next (/home/as/.npm/_npx/22659/lib/node_modules/elm-app/node_modules/express/lib/router/index.js:275:10)
    at query (/home/as/.npm/_npx/22659/lib/node_modules/elm-app/node_modules/express/lib/middleware/query.js:45:5)
    at Layer.handle [as handle_request] (/home/as/.npm/_npx/22659/lib/node_modules/elm-app/node_modules/express/lib/router/layer.js:95:5)
    at trim_prefix (/home/as/.npm/_npx/22659/lib/node_modules/elm-app/node_modules/express/lib/router/index.js:317:13)
    at /home/as/.npm/_npx/22659/lib/node_modules/elm-app/node_modules/express/lib/router/index.js:284:7
    at Function.process_params (/home/as/.npm/_npx/22659/lib/node_modules/elm-app/node_modules/express/lib/router/index.js:335:12)

Environment

1. node -v: v11.14.0
2. npm -v: 6.10.1
3. yarn --version (if you use Yarn):
4. npm ls create-elm-app -g (if you haven’t ejected): empty (using npx)

Then, specify:

1. Operating system: Ubuntu 18.04
2. Browser and version (if relevant): Not relevant

I'm also using a node package manager called fnm (1.12.0). The behavior does not occur when create-elm-app is installed globally, instead of npx. That's why I would think it's related to npx, but I wanted to mention this.

Steps to Reproduce

1. npx create-elm-app@latest test-project
2. cd test-project
3. npx elm-app@latest start

Expected Behavior

It's starting the application without errors/warnings

Actual Behavior

It's starting, but there are issues shown in the console. The issues are related to string replacement.

What else to say

I think this could be specific to npx and maybe there is no way to solve it. But maybe there is? :)