add support for ESM default export in hooks

docs/authoring.md

@@ -394,9 +394,9 @@ In case you have more than one template and want to reuse filters, you can put t
 
 ## TypeScript support 
 
-The AsyncAPI generator has support for the TypeScript for [hooks](#hooks) and Nunjucks's [filters](#filters). Assumptions:
+The AsyncAPI generator has TypeScript support for [hooks](#hooks) and Nunjucks's [filters](#filters). Assumptions:
 
 - Installing the `typescript` package and creating the` tsconfig.json` file isn't necessary.
-- Source code of the hook/filter must have `ts` extension.
-- Each package related with the typings for TypeScript like `@types/node` must be installed in the template under `dependencies` array. This is because the Generator transpiles the TypeScript code on-the-fly while rendering the template.
+- Source code of the hook/filter must have `.ts` extension.
+- Each package related with the typings for TypeScript like `@types/node` must be installed in the template under `dependencies` array. This is because the Generator transpiles the TypeScript code on-the-fly while rendering the template, so cannot uses packages under `devDependencies`.
 - Each package should have installed `@types/node` package to support typings for Node.

lib/hooksRegistry.js

@@ -98,6 +98,11 @@ async function registerConfigHooks(hooks, templateDir, templateConfig) {
  * @param {Array} config List of hooks configured in template configuration
  */
 function addHook(hooks, mod, config) {
+  // for ESM `export default {}`
+  if (typeof mod.default === 'object') {
+    mod = mod.default;
+  }
+
   Object.keys(mod).forEach(hookType => {
     const moduleHooksArray = [].concat(mod[hookType]);