fix: handle ESM-style config file

[quantizor]

Fixes happo/happo-e2e#50

Note that this PR doesn't change how the file itself is loaded to completely settle ESM compat, but it at least makes the CLI work properly when used in conjunction with NODE_OPTIONS='--experimental-require-module'

[quantizor]

This is the quick & dirty patch I made via yarn patch to fix this + get rid of the need for the NODE_OPTIONS override:

--- a/build/loadUserConfig.js
+++ b/build/loadUserConfig.js
@@ -14,10 +14,12 @@ function _interopRequireWildcard(obj, nodeInterop) { if (!nodeInterop && obj &&
 function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
 async function load(pathToConfigFile) {
   try {
-    let userConfig = (0, _requireRelative.default)(pathToConfigFile, process.cwd());
+    let userConfig = await import(process.cwd() + pathToConfigFile.slice(1));
     // await if the config is a function, async or not
     if (typeof userConfig === 'function') {
       userConfig = await userConfig();
+    } else if (userConfig?.default) {
+      userConfig = userConfig.default;
     }
     return {
       ...defaultConfig,

Probably need to pull in path.resolve for the import to fix it properly.

[lencioni]

Thank you so much for the fix!

[lencioni]

@quantizor would you be interested in working on a PR to handle the rest of the ESM compat?

[quantizor]

@quantizor would you be interested in working on a PR to handle the rest of the ESM compat?

Last few work days before winter vacation, this is my contribution for now 😊

[lencioni]

Sounds great, thank you again! I'll get this published now then.