fix: Allow processors to add scoped package imports

lib/utils.js

@@ -1,5 +1,5 @@
 "use strict";
-const path = require("path");
+const { extname } = require("path");
 
 function getDefault(dflt) {
   switch (dflt.type) {
@@ -70,16 +70,20 @@ function toKey(type, func = "") {
   return String(func + type).replace(/[./-]+/g, " ").trim().replace(/ /g, "_");
 }
 
+const PACKAGE_NAME_REGEX = /^(?:@([^/]+?)[/])?([^/]+?)$/u;
+
 class RequiresMap extends Map {
   constructor(ctx) {
     super();
     this.ctx = ctx;
   }
 
-  add(type, func = "") {
-    const key = toKey(type, func);
+  add(name, func = "") {
+    const key = toKey(name, func);
 
-    const importPath = (type.includes("/") || type.startsWith(".")) && !path.extname(type) ? type + ".js" : type;
+    // If `name` is a package name or has a file extension, then use it as-is,
+    // otherwise append the `.js` file extension:
+    const importPath = PACKAGE_NAME_REGEX.test(name) || extname(name) ? name : `${name}.js`;
     let req = `require(${JSON.stringify(importPath)})`;
 
     if (func) {
@@ -93,8 +97,8 @@ class RequiresMap extends Map {
   addRelative(type, func = "") {
     const key = toKey(type, func);
 
-    const importPath = type.startsWith(".") ? type : `./${type}`;
-    let req = `require("${importPath}.js")`;
+    const path = type.startsWith(".") ? type : `./${type}`;
+    let req = `require("${path}.js")`;
 
     if (func) {
       req += `.${func}`;