This looks like a bug with the prefix package (which is a dependency of simple-color-picker). The package.json of the prefix package is using the browser field, which points to the packages browser.js file. This file is then excluded however by the files field (which is only allowing index.js).
This is why meteor is complaining about not being able to find the browser.js file (it doesn’t exist locally). I’d suggest opening an issue with the prefix project.
No problem - just to add; I’m not 100% sure that files is the issue, but I can verify that the browser.js file is missing from the local prefix package, so I’m assuming it’s something like that. Regardless, the package author should be able to help verify.