refactor: improve toClassName function readability and JSDoc completeness

- Replaced substr with slice for better readability and consistency.
- Updated JSDoc to include @param and @returns tags for clarity on function inputs and outputs.
- Simplified the conditional logic by using slice(-5) === 'Error' for a concise and clear check.

Author: Ayoub-Mabrouk

HISTORY.md

@@ -1,3 +1,8 @@
+Unreleased changes
+==================
+
+  * improve toClassName function readability and JSDoc completeness
+
 2.0.0 / 2021-12-17
 ==================
 

index.js

@@ -279,11 +279,12 @@ function populateConstructorExports (exports, codes, HttpError) {
 
 /**
  * Get a class name from a name identifier.
+ *
+ * @param {string} name
+ * @returns {string}
  * @private
  */
 
 function toClassName (name) {
-  return name.substr(-5) !== 'Error'
-    ? name + 'Error'
-    : name
+  return name.slice(-5) === 'Error' ? name : name + 'Error'
 }