From dc38b52a3ead6e3f65e937f584d21ed1689b6c5d Mon Sep 17 00:00:00 2001
From: Stanislav A <s.atroschenko@adguard.com>
Date: Thu, 15 Dec 2022 21:41:26 +0300
Subject: [PATCH] refactor and update readme

---
 README.md               |  5 +++--
 src/scriptlets/index.js | 10 ++++++----
 2 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/README.md b/README.md
index af622964..24c3ca5a 100644
--- a/README.md
+++ b/README.md
@@ -161,9 +161,10 @@ And also there is a module at `dist/scriptlets.js` which has been exported to a
 
 ```javascript
 /**
- * Returns scriptlet code
+ * Returns scriptlet code by param
  * @param {Source} source
- * @returns {string}
+ * @returns {string|null} scriptlet code
+ * @throws on unknown scriptlet name
  */
 scriptlets.invoke(source);
 ```
diff --git a/src/scriptlets/index.js b/src/scriptlets/index.js
index 52508664..c2ca22f7 100644
--- a/src/scriptlets/index.js
+++ b/src/scriptlets/index.js
@@ -29,20 +29,22 @@ import { getScriptletFunction } from '../../tmp/scriptlets-func';
  * Returns scriptlet code by param
  * @param {Source} source
  * @returns {string|null} scriptlet code
+ * @throws on unknown scriptlet name
  */
 function getScriptletCode(source) {
     if (!validator.isValidScriptletName(source.name)) {
         return null;
     }
 
-    const scriptletFunction = getScriptletFunction(source.name)?.toString();
-    if (!scriptletFunction) {
+    const scriptletFunction = getScriptletFunction(source.name);
+    if (typeof scriptletFunction !== 'function') {
         throw new Error(`Error: cannot invoke scriptlet with name: '${source.name}'`);
     }
+    const scriptletFunctionString = scriptletFunction.toString();
 
     const result = source.engine === 'corelibs' || source.engine === 'test'
-        ? wrapInNonameFunc(scriptletFunction)
-        : passSourceAndProps(source, scriptletFunction);
+        ? wrapInNonameFunc(scriptletFunctionString)
+        : passSourceAndProps(source, scriptletFunctionString);
     return result;
 }