Created by: leebyron
Support for .mjs files added in #3239 did not account for npm libraries which ship native mjs files alongside js files. This accounts for this by ensuring .js files resolve before their accompanying .mjs file. Note that this is not an ideal end state since selecting a .mjs over a .js extension should be the result of whether import was used instead of require() in a node environment with native ESM support (currently via --experimental-modules). Instead, this change just always selects a .js extension before the .mjs extension if it exists.
This unbreaks support for using GraphQL (relay, apollo, etc) within create-react-app projects.