fix: use file:// url loading plugins

The `file://` url is used when the path is not a relative path.  This
supports all platforms.

Signed-off-by: Chris. Webster <chris@webstech.net>

lib/plugins/utils.js

@@ -52,9 +52,14 @@ export async function loadPlugin({cwd}, name, pluginsPath) {
     ? dirname(resolveFrom.silent(__dirname, pluginsPath[name]) || resolveFrom(cwd, pluginsPath[name]))
     : __dirname;
 
-  // See https://github.com/mysticatea/eslint-plugin-node/issues/250
-  // eslint-disable-next-line node/no-unsupported-features/es-syntax
-  return isFunction(name) ? name : (await import(resolveFrom.silent(basePath, name) || resolveFrom(cwd, name))).default;
+  if (!isFunction(name)) {
+    const file = resolveFrom.silent(basePath, name) || resolveFrom(cwd, name);
+    // See https://github.com/mysticatea/eslint-plugin-node/issues/250
+    // eslint-disable-next-line node/no-unsupported-features/es-syntax
+    name = (await import(`${ file[0] != '.' ? "file://" : "" }${file}`)).default;
+  }
+
+  return name;
 }
 
 export function parseConfig(plugin) {